Bosnianbill's YouTube channel has featured some nifty "unpickable" designs:

* Inaccessible keyhole: https://invidio.us/watch?v=OLsJDELd4lo

Sounds related to the lock you describe, except this one is purely mechanical.

* Serpentine keyhole: https://invidio.us/watch?v=1ey2SFHbZV8