replace xscreensaver with light locker?

[Scott(0)]

I can confirm this works and the keyboard shortcut is already there.

The shortcut is:
Super + L

The super key is the Windows logo key.

Or

Menu > Settings > Keyboard > Applications Shortcuts Tab

In the command column look for
xflock4

In the shortcut column
Super+L

This is where you can make new shortcuts or change existing shortcuts.