How to change the timezone manipulate the timestamp of created_at

I have an eloquent query that I would want to change the created_at to subtract 2 hours.

The query is

AirtimeTransaction::select('airtime_transactions.id',
   'airtime_transactions.created_at',
   'airtime_transactions.request_id', 
   DB::raw('IF(airtime_transactions.result_desc IS NULL or airtime_transactions.result_desc = "", "Failed", airtime_transactions.result_desc) as result_desc'))
->groupBy('airtime_transactions.id');

I would like to subtract two hours from the answer to airtime_transactions.created_at

Anyone assist here

via Chebli Mohamed