Try this:
<?php
date_default_timezone_set('Asia/Calcutta'); # set timezone according to your requirement
$now = new DateTime();
$start = new DateTime('today 08:00:00');
$end = new DateTime('tomorrow 00:30:00');
if ($start <= $now && $now < $end) {
echo "open";
}
else{
echo "close";
}
?>