Keyboard shortcut to disable keyboard
It would be interesting to know where that information came from, as, as far as I am aware, it is totally incorrect. 

These are Accessibility Controls...
Opt x5 is to enable Mouse Keys; that allows your 10-key pad to act like a mouse.
Ctrl/F1 I think you are confusing with "Full Keyboard Access" which allows more complete navigation using only the keyboard.

It Toggles between this :-



and this



The only way I know to actually disable it is to use a utility called KeyboardCleanTool [freeware]