[Towncar]

I'm not aware of any OEM locking lugnuts.
That would make them aftermarket stuff. Take the car to ANY tire shop. They have a tool that can remove them without damage to the wheels, etc.
Trash them.
You can replace then with stock, or buy another aftermarket set.

Even if you could ID them with mfg's #'s or whatever, no-one's going to give you a key, they just don't do that.