So we got the reply from the current owners, they do not have any such card for the keys.
You need to find out which Kaba key it is. Some can be copied, others not.
For example, my Kaba lock on my fence gate I can get copied, but not my front door key.
You are not being paranoid. In fact, many people are unaware that if you cannot account for all the keys, your insurance coverage may be void should you have a robbery with no sign of a break in.
At the moment only the current owners can find out about the keys, or the notary can do so on your behalf.
Edit: as the apartment is only 5 years old, it is quite possible the builder has the key information .
Update: The owners have found the card and they will hand it over with the Keys. Thank you again for all the inputs, I always wonder what I would do without EF.