add index in laravel migration

1$table->index(['account_id', 'created_at']);

1<?php
2
3use Illuminate\Database\Migrations\Migration;
4use Illuminate\Database\Schema\Blueprint;
5use Illuminate\Support\Facades\Schema;
6use Illuminate\Support\Facades\DB;
7
8class Products extends Migration
9{
10    /**
11     * Run the migrations.
12     *
13     * @return void
14     */
15    public function up()
16    {
17        Schema::create('products', function (Blueprint $table) {
18            $table->id();
19            $table->string('product_name')->index('product_name');
20            $table->string('product_sku')->index('product_sku');
21        });
22    }
23
24    /**
25     * Reverse the migrations.
26     *
27     * @return void
28     */
29    public function down()
30    {
31        Schema::dropIfExists('products');
32    }
33}