keyboard shortcut is driving me crazy, how do I get rid of it?
There is already a system wide keyboard shortcut to lock your display. It's CommandControlQ for High Sierra and higher and ControlShift⏏ on other systems, to let your display go to sleep (which is effectively the same when password protected). 

With this keyboard shortcuts in mind you can be sure, that they don't interfere with any application.

Note that on newer MacsBook Pros with Touch ID only the first keyboard shortcut works.