Be warned, MySQL prior to versions 5.7.3 do not require the server to use SSL [1]. In the case of PHP the client won't throw an error if the connection is downgraded to plain-text [2]
[1] https://dev.mysql.com/doc/refman/5.7/en/encrypted-connection-options.html#option_general_ssl
[2] http://www.idontplaydarts.com/2015/03/mysql-with-ssl-does-not-protect-against-active-mitm/