How to add column index in Laravel?

I have tried this in my migration but it does not work as expected.

$table->string('key')->primary()->index();

I also tried to use chatgpt but no solutions were correct. So I hit brick wall debugging, I know its something obvious I am missing.

>Solution :

Welcome to SO, its been answered before but the simples way to index your column is to add this in a new migration, so firstly create a migration like

php artisan make:migration add_index_to_key_column_on_table

and in that migration

Schema::table('table', function (Blueprint $table) {
    $table->index(['key']);
});