My understanding of the locks (all of them) on Kaisers was that all locks on any given car could be activated by the ignition key...the additional key was meant as a spare.
Of course, that doesn't mean a previous owner of your car couldn't have changed one or more locks on it, or had them re-keyed for some reason.
I know this doesn't really help with your situation, but I would think a competent locksmith should be able to open it, and if the lock is not damaged in some way (that is, the lock is fully functional...a good locksmith should be able to open it without damage), make you the appropriate key for it.