Steps to reproduce:

1. Create MySQL server that accepts only TLS requests, (require_secure_transport=ON)
2. Create MySQL user with super-admin rights (any rights should be enough as long as it can connect with TLS)
3. Set up mysql configuration in Zabbix agent 2 for connection with 

   1. Plugins.Mysql.Sessions.TLSRequiredSession.TLSConnect=required

   2. Can use another Session for none TLS connect, or use defaults or connect via key
   3. We need two requests one with TLS, one without, set up doesnot matter, as long as the host, user and password they the same between the requests.
4. Start Zabbix agent 2
5. Call mysql.ping[*] with non TLS set up
6. Call mysql.ping[] with TLS set up

Result:

Connection will fail, as connection is set with user/password combo and doesnt take tls into account, so Zabbix agent 2 will try to connect with the already existing connection that doesn't have TLS support and the connection will fail.

Expected:
Successfully get result.

P.S Similar issue might be present in other plugins with this type of connection set-up.