- date_default_timezone_set: documentation ( source)
<?php
date_default_timezone_set('Europe/Moscow');
echo $paydate = (new DateTime("2016-06-11 02:02:00"))->format('Y-m-d H:i:s');
echo "\r\n";
echo $todaydate = (new DateTime("now"))->format('Y-m-d H:i:s');
echo "\r\n";
echo "\r\n";
echo $diff = $todaydate->diff($paydate);