$re = '/\bdelay\s*:\s*\'(\d{4}-\d{1,2}-\d{1,2})\s*([^\']*)\'/m';
$str = 'ticket:1 priority:5 delay:\'2019-08-31 02:53:27.720422\' delay:\'2019-08-30 00:04:10.681242\'';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php