multiple connections on MySQL database with no users on httpd
You will need to look into how your connection pool is configured in your PHP web app. Even a fully functional connection pool will often keep many connections to a database open even when they are not in use.  Opening connections to the database can be very expensive for a web app and it makes sense to have some unused ones sitting around.

Most connection pools have settings for things like:


Minimum number of connections to keep open
Maximum number of connections to keep open
Number of connections to open when new connections are needed




There is also the possibility that your web app is not releasing connections back to the connection pool properly.  When you are done with your connections, you need to close them to let the pool know that they are available.   Not doing so is a a kind of resource leak and you will eventually run out of connections.