- var_dump: documentation ( source)
- time: documentation ( source)
- strtotime: documentation ( source)
<?php
$promo_date = array(
'start' => '2016-03-25 00:00:00',
'end' => '2016-05-31 23:59:59'
);
$time = time();
var_dump($time >= strtotime($promo_date['start']));