$re = '/(?:call|CALL)[\ *](?:(?:system|"system").(?:runtime|"runtime").(?:kill_query|"kill_query"))/m';
$str = 'CALL system.runtime.kill_query(query_id => \'20211003_215635_15007_n3mb3\', message => \'Looker query cancel.\')
CALL "system"."runtime"."kill_query"(query_id => \'20211003_215635_15007_n3mb3\', message => \'Looker query cancel.\')
CALL "system".runtime."kill_query"(query_id => \'20211003_215635_15007_n3mb3\', message => \'Looker query cancel.\')
CALL "system"."runtime"."kill_query"(\'20211003_215635_15007_n3mb3\', \'afsd\')
CALL "system"."runtime"."kill_query"(message => \'20211003_215635_15007_n3mb3\', query_id => \'afsd\')
CALL+"system"."runtime"."kill_query"(message => \'20211003_215635_15007_n3mb3\', query_id => \'afsd\')';
preg_match_all($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