I think best practice is that you use a separate (dedicated running) process running on a machine/vm to catch the MQTT data from your nodes and insert it in your own MySQL DB .. then, a PHP based webpage could be made to fetch the data from your MySQL db and present it to the user.
that separate process that catches the MQTT data could also be running in PHP (mosquitto PHP clients do exist), but I think most devs would prefer other languages for that