What I did/do is this:
Go into to "Keychain Access" (search it in spotlight) and set it to show it's status in the Menu Bar.
Then click on the icon in the Menu Bar (the lock) and "Lock Screen".
Then the screen saver comes up.
Then move your mouse so you get to the screen to unlock your Mac.
Press "Control, Shift, Eject" and then hit "Cancel".
This should work; it does on mine.
If it doesn't work try alternatives of hitting "control, shift, eject" right away, afterwards etc.