diff --git a/app/Models/Foundation/Summit/Repositories/ISummitOrderRepository.php b/app/Models/Foundation/Summit/Repositories/ISummitOrderRepository.php
index 6c220b838..5a6c20410 100644
--- a/app/Models/Foundation/Summit/Repositories/ISummitOrderRepository.php
+++ b/app/Models/Foundation/Summit/Repositories/ISummitOrderRepository.php
@@ -35,12 +35,6 @@ public function getByHashLockExclusive(string $hash): ?SummitOrder;
      */
     public function getByPaymentGatewayCartIdExclusiveLock(string $payment_gateway_cart_id): ?SummitOrder;
 
-    /**
-     * @param string $externalId
-     * @return SummitOrder|null
-     */
-    public function getByExternalIdLockExclusive(string $externalId):?SummitOrder;
-
     /**
      * @param Summit $summit
      * @param string $externalId
@@ -48,12 +42,6 @@ public function getByExternalIdLockExclusive(string $externalId):?SummitOrder;
      */
     public function getByExternalIdAndSummitLockExclusive(Summit $summit, string $externalId):?SummitOrder;
 
-    /**
-     * @param string $email
-     * @return mixed
-     */
-    public function getAllByOwnerEmail(string $email);
-
     /**
      * @param string $email
      * @return mixed
diff --git a/app/Repositories/Summit/DoctrineSummitOrderRepository.php b/app/Repositories/Summit/DoctrineSummitOrderRepository.php
index 317bbe5cd..9bf67cd96 100644
--- a/app/Repositories/Summit/DoctrineSummitOrderRepository.php
+++ b/app/Repositories/Summit/DoctrineSummitOrderRepository.php
@@ -89,25 +89,6 @@ public function getByPaymentGatewayCartIdExclusiveLock(string $payment_gateway_c
             ->getOneOrNullResult();
     }
 
-    /**
-     * @param string $email
-     * @return mixed
-     */
-    public function getAllByOwnerEmail(string $email)
-    {
-        $query = $this->getEntityManager()
-            ->createQueryBuilder()
-            ->select("e")
-            ->from($this->getBaseEntity(), "e")
-            ->where("e.owner_email = :owner_email");
-
-        $query->setParameter("owner_email", trim($email));
-        return $query->getQuery()
-            ->setLockMode(\Doctrine\DBAL\LockMode::PESSIMISTIC_WRITE)
-            ->setHint(\Doctrine\ORM\Query::HINT_REFRESH, true)
-            ->getResult();
-    }
-
     /**
      * @param string $email
      * @return mixed
@@ -174,25 +155,6 @@ public function getAllConfirmedOlderThanXMinutes(int $minutes, int $max = 100)
 
     }
 
-    /**
-     * @param string $externalId
-     * @return SummitOrder|null
-     */
-    public function getByExternalIdLockExclusive(string $externalId): ?SummitOrder
-    {
-        $query = $this->getEntityManager()
-            ->createQueryBuilder()
-            ->select("e")
-            ->from($this->getBaseEntity(), "e")
-            ->where("e.external_id = :external_id");
-
-        $query->setParameter("external_id", $externalId);
-        return $query->getQuery()
-            ->setLockMode(\Doctrine\DBAL\LockMode::PESSIMISTIC_WRITE)
-            ->setHint(\Doctrine\ORM\Query::HINT_REFRESH, true)
-            ->getOneOrNullResult();
-    }
-
     /**
      * @param Summit $summit
      * @param string $externalId
diff --git a/database/migrations/model/Version20261022120000.php b/database/migrations/model/Version20261022120000.php
new file mode 100644
index 000000000..5858f8854
--- /dev/null
+++ b/database/migrations/model/Version20261022120000.php
@@ -0,0 +1,61 @@
+<?php namespace Database\Migrations\Model;
+/**
+ * Copyright 2026 OpenStack Foundation
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ **/
+
+use Database\Utils\DBHelpers;
+use Doctrine\Migrations\AbstractMigration;
+use Doctrine\DBAL\Schema\Schema as Schema;
+use Illuminate\Support\Facades\DB;
+
+/**
+ * Class Version20261022120000
+ *
+ * - IDX_SummitOrder_OwnerEmail_Owner supports DoctrineSummitOrderRepository::getAllByOwnerEmailAndOwnerNotSet()
+ *   (WHERE OwnerEmail = ? AND OwnerID IS NULL); OwnerEmail is only the third column of
+ *   IDX_SummitOrder_OwnerFields_Summit, so the optimizer scanned every ownerless order through the OwnerID index.
+ * - IDX_SummitOrder_Hash and IDX_SummitOrder_PaymentGatewayCartId support getByHashLockExclusive() and
+ *   getByPaymentGatewayCartIdExclusiveLock(); without them the PESSIMISTIC_WRITE lookups scan (and lock) the whole table.
+ *
+ * @package Database\Migrations\Model
+ */
+class Version20261022120000 extends AbstractMigration
+{
+    private const Indexes = [
+        'IDX_SummitOrder_OwnerEmail_Owner' => '`OwnerEmail`, `OwnerID`',
+        'IDX_SummitOrder_Hash' => '`Hash`',
+        'IDX_SummitOrder_PaymentGatewayCartId' => '`PaymentGatewayCartId`',
+    ];
+
+    /**
+     * @param Schema $schema
+     */
+    public function up(Schema $schema): void
+    {
+        $db = DB::connection("model")->getDatabaseName();
+        foreach (self::Indexes as $name => $columns) {
+            if (!DBHelpers::existsIDX($db, 'SummitOrder', $name)) {
+                $this->addSql("ALTER TABLE `SummitOrder` ADD INDEX `{$name}` ({$columns}) USING BTREE, ALGORITHM=INPLACE, LOCK=NONE;");
+            }
+        }
+    }
+
+    public function down(Schema $schema): void
+    {
+        $db = DB::connection("model")->getDatabaseName();
+        foreach (self::Indexes as $name => $columns) {
+            if (DBHelpers::existsIDX($db, 'SummitOrder', $name)) {
+                $this->addSql("ALTER TABLE `SummitOrder` DROP INDEX `{$name}`;");
+            }
+        }
+    }
+}
diff --git a/tests/DoctrineSummitOrderRepositoryIndexesTest.php b/tests/DoctrineSummitOrderRepositoryIndexesTest.php
new file mode 100644
index 000000000..982470ea4
--- /dev/null
+++ b/tests/DoctrineSummitOrderRepositoryIndexesTest.php
@@ -0,0 +1,82 @@
+<?php namespace Tests;
+/**
+ * Copyright 2026 OpenStack Foundation
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ **/
+
+use LaravelDoctrine\ORM\Facades\Registry;
+use models\utils\SilverstripeBaseModel;
+
+/**
+ * Covers the SummitOrder indexes behind getAllByOwnerEmailAndOwnerNotSet(), getByHashLockExclusive()
+ * and getByPaymentGatewayCartIdExclusiveLock(). The index columns are checked in
+ * INFORMATION_SCHEMA and the predicates are explained to check the optimizer can pick them (possible_keys).
+ *
+ * Class DoctrineSummitOrderRepositoryIndexesTest
+ */
+final class DoctrineSummitOrderRepositoryIndexesTest extends TestCase
+{
+    private function connection()
+    {
+        return Registry::getManager(SilverstripeBaseModel::EntityManager)->getConnection();
+    }
+
+    private function indexColumns(string $index): array
+    {
+        $rows = $this->connection()->fetchAllAssociative(
+            "SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.STATISTICS
+             WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'SummitOrder' AND INDEX_NAME = ?
+             ORDER BY SEQ_IN_INDEX",
+            [$index]
+        );
+        return array_column($rows, 'COLUMN_NAME');
+    }
+
+    private function explainPossibleKeys(string $sql, array $params): string
+    {
+        $rows = $this->connection()->fetchAllAssociative("EXPLAIN " . $sql, $params);
+        return (string)($rows[0]['possible_keys'] ?? '');
+    }
+
+    public function testOwnerEmailOwnerIndexExists(): void
+    {
+        $this->assertSame(['OwnerEmail', 'OwnerID'], $this->indexColumns('IDX_SummitOrder_OwnerEmail_Owner'));
+    }
+
+    public function testHashIndexExists(): void
+    {
+        $this->assertSame(['Hash'], $this->indexColumns('IDX_SummitOrder_Hash'));
+    }
+
+    public function testPaymentGatewayCartIdIndexExists(): void
+    {
+        $this->assertSame(['PaymentGatewayCartId'], $this->indexColumns('IDX_SummitOrder_PaymentGatewayCartId'));
+    }
+
+    public function testAssociationLookupCanUseOwnerEmailOwnerIndex(): void
+    {
+        $keys = $this->explainPossibleKeys(
+            "SELECT ID FROM SummitOrder WHERE OwnerEmail = ? AND OwnerID IS NULL", ['a@b.com']);
+        $this->assertStringContainsString('IDX_SummitOrder_OwnerEmail_Owner', $keys);
+    }
+
+    public function testHashLookupCanUseHashIndex(): void
+    {
+        $keys = $this->explainPossibleKeys("SELECT ID FROM SummitOrder WHERE Hash = ?", ['x']);
+        $this->assertStringContainsString('IDX_SummitOrder_Hash', $keys);
+    }
+
+    public function testCartIdLookupCanUseCartIdIndex(): void
+    {
+        $keys = $this->explainPossibleKeys("SELECT ID FROM SummitOrder WHERE PaymentGatewayCartId = ?", ['x']);
+        $this->assertStringContainsString('IDX_SummitOrder_PaymentGatewayCartId', $keys);
+    }
+}