No, if the process has hung for that long, it is obviuosly not doing anything useful. If your nervous just stop mysql , Asterisk has no need for it, so your system runs as ever, probably smoother.
At any time, you can use mysql’s ‘show process’ procedure, profiling mysql might help you here
https://dev.mysql.com/doc/refman/5.5/en/show-profile.html
so you will need to pre-prepare your system , then watch for all the WTFs