$re = '/([^,\s\{=]+)=([^,]*)(?=,|\})/m';
$str = '{af_sub1=1.5, af_deeplink=true, campaign=None, media_source=None, install_time=2018-05-08 03:34:34, af_status=Non-organic, path=, scheme=, host=}';
preg_match_all($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