Why renaming timestamps columns do not work?

I am renaming the created_at and updated columns to createdAt and updatedAt respectively but it does not work.

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class MyModel extends Model
{
    const CREATED_AT = 'createdAt';
    const UPDATED_AT = 'updatedAt';
}

And this is how I get the resources:

public function index()
{
    return response(MyModel::all());
}

Using PHP Lumen 5.8

via Chebli Mohamed