<?php
$current_time = '4:00';
$time_slot = ['1:00','3:00','15:00','19:00'];
$current_date = new \DateTime($current_time);
foreach($time_slot as $index => $value) {
if ($current_date > new \DateTime
($value)) unset($time_slot[$index]); }
PD9waHAKCiRjdXJyZW50X3RpbWUgPSAnNDowMCc7CiR0aW1lX3Nsb3QgPSBbJzE6MDAnLCczOjAwJywnMTU6MDAnLCcxOTowMCddOwoKJGN1cnJlbnRfZGF0ZSA9IG5ldyBcRGF0ZVRpbWUoJGN1cnJlbnRfdGltZSk7Cgpmb3JlYWNoKCR0aW1lX3Nsb3QgYXMgICRpbmRleCA9PiAkdmFsdWUpIHsKCWlmICgkY3VycmVudF9kYXRlID4gbmV3IFxEYXRlVGltZSgkdmFsdWUpKSB1bnNldCgkdGltZV9zbG90WyRpbmRleF0pOwp9CnZhcl9kdW1wKCR0aW1lX3Nsb3QpOw==