Check services that are enabled on CentOS 7

# systemctl list-unit-files

Or for a specific service

# systemctl status mysqld

Disabling a service on boot in CentOS 7
To disable, it’s simply a matter of running systemctl disable on the desired service.

# systemctl disable mysqld

Check which services failed to start on boot on CentOS 7
As a bonus, systemctl allows you to list all services that failed to start on boot, even though they were configured to start on boot.

# systemctl --failed