Is there a keyboard shortcut for the System Preferences lock?
While there is no explicit keypress that will take you directly to the Lock icon that I know of, you can hit the Tab key repeatedly to select the tabs and checkboxes in a System Preferences window (I tested with the Security &amp; Privacy window) and end up at the Lock icon, which is then selected.

Not selected:



Selected:



Hit the Space bar, and the lock opens to the credentials login.



You will need to have System Preferences > Keyboard > Shortcuts > Full Keyboard Access > All controls radio button selected:



Thanks, Nimesh, for pointing out this radio button. I had it enabled, but did not realize it.