diff --git a/keyserver/src/cron/cron.js b/keyserver/src/cron/cron.js
--- a/keyserver/src/cron/cron.js
+++ b/keyserver/src/cron/cron.js
@@ -27,7 +27,7 @@
 
 if (cluster.isMaster) {
   schedule.scheduleJob(
-    '30 3 * * *', // every day at 3:30 AM Pacific Time
+    '30 3 * * *', // every day at 3:30 AM GMT
     async () => {
       try {
         // Do everything one at a time to reduce load since we're in no hurry,
diff --git a/keyserver/src/database/migration-config.js b/keyserver/src/database/migration-config.js
--- a/keyserver/src/database/migration-config.js
+++ b/keyserver/src/database/migration-config.js
@@ -216,6 +216,17 @@
       `);
     },
   ],
+  [
+    21,
+    async () => {
+      await dbQuery(SQL`
+        ALTER TABLE reports
+          DROP INDEX IF EXISTS user,
+          ADD INDEX IF NOT EXISTS user_type_platform_creation_time
+            (user, type, platform, creation_time);
+      `);
+    },
+  ],
 ]);
 const newDatabaseVersion: number = Math.max(...migrations.keys());
 
diff --git a/keyserver/src/database/setup-db.js b/keyserver/src/database/setup-db.js
--- a/keyserver/src/database/setup-db.js
+++ b/keyserver/src/database/setup-db.js
@@ -292,7 +292,9 @@
       ALTER TABLE notifications ADD INDEX user (user);
 
       ALTER TABLE reports
-        ADD PRIMARY KEY (id);
+        ADD PRIMARY KEY (id),
+        ADD INDEX user_type_platform_creation_time
+          (user, type, platform, creation_time);
 
       ALTER TABLE revisions
         ADD PRIMARY KEY (id),