order_issues 添加字段 archive_at 归档日期添加索引

database/migrations/2021_04_20_145634_add_archive_at_to_order_issues_table.php

@@ -14,7 +14,7 @@ class AddArchiveAtToOrderIssuesTable extends Migration
     public function up()
     {
         Schema::table('order_issues', function (Blueprint $table) {
-            $table->timestamp('archive_at')->nullable()->comment('归档事件');
+            $table->timestamp('archive_at')->index()->nullable()->comment('归档事件');
         });
     }