How to correctly add an index to mysql database columns?

I am trying to master index columns in data base. But, in my opinion, nothing works for me.

I create a table specifically for the test:

public function up()
    {
        Schema::create('products', function (Blueprint $table) {
            $table->id();
            $table->string('name', 50);
            $table->string('color')->index();
            $table->string('gender');
            $table->unsignedBigInteger('old_price')->index();
            $table->unsignedBigInteger('price');

            $table->timestamps();
        });
    }

create a table specifically for the test:

public function definition()
    {
        return [
            'name' => $this->faker->text(50),
            'color' => $this->faker->randomElement(['white', 'black']),
            'gender' => $this->faker->randomElement(['man', 'woman', 'boy']),
            'old_price' => $this->faker->numberBetween(11,14),
            'price' => $this->faker->numberBetween(15,18),
            ];
    }

Launching the seeder:

public function run()
    {
        Product::factory(500000)->create();
    }

After that, I alternately try to find some results. But I don't notice the time difference. Columns that are in the index are loaded the same as without the index.

$products = Produst::select()
            ->where('color', 'white')
            //->where('gender', 'woman')
            //->where('price', '15')
            //->where('old_price', '18')
            ->get();
        dump($products );
        $loadingTime = round(microtime(true) - LARAVEL_START, 3);
        echo $loadingTime ;
        dd();

This data is loaded in about 8 seconds. What am I doing wrong? What? I do not understand? Thank you in advance!