diff --git a/spindle/db/db.go b/spindle/db/db.go
index 9d4512d3..18463a91 100644
--- a/spindle/db/db.go
+++ b/spindle/db/db.go
@@ -943,6 +943,13 @@ func runMigrations(_ context.Context, conn *sql.Conn, logger *slog.Logger) error
 		return err
 	}
 
+	if err := orm.RunMigration(conn, logger, "schedule-runs-prune-index", func(tx *sql.Tx) error {
+		_, err := tx.Exec(`create index if not exists idx_schedule_runs_prune on schedule_runs(scheduled_at)`)
+		return err
+	}); err != nil {
+		return err
+	}
+
 	if err := orm.RunMigration(conn, logger, "workflow-schedules-timezone", func(tx *sql.Tx) error {
 		var hasTimezone int
 		if err := tx.QueryRow(