You can enable a general query log for that sort of diagnostic. Generally you don’t log all SELECT queries on a production server though, it’s a performance killer.
Edit your MySQL config, e.g. /etc/mysql/my.cnf – look for, or add, a line like this:

[mysqld]
log = /var/log/mysql/mysql.logCode language: JavaScript (javascript)

Restart mysql to pick up that change, now you can:

tail -f /var/log/mysql/mysql.logCode language: JavaScript (javascript)

Hey presto, you can watch the queries as they come in.