I found mine in Budapest, it is not far away from the Slovak border. I found this species in my older book also, so it is a well known species in Hungary. It has a slightly different name in the older books Prenolepis imparis var. nitens.
You can read from the American kind Prenolepis imparis a lot in the internet. If you find something interesting about keeping them, let me know.
I hope its life is similar here than its American cousin. The American ant (winter ant or little honey ant) life is very different from most of the other ant. It is foraging in winter from November to April, otherwise it is completely closed up.
You can read everything from here:
http://bio.fsu.edu/~tschink/publications/1987-3.pdf
By the way two other guys from the Hungarian forum also found a queen. I'm hope somebody can raise it to a full colony.