Yes,
it is within walking distance from main train station. I will ask my friend for exact address. I saw it, but the shop was closed (I found it in early evening).
If you will have some more time in center, I reccomend Roman museum:
www.museenkoeln.de
The museum was built on the walls of a Roman villa which was discovered in 1941 and which contained the world-famous Dionysos mosaic. The discovery was done during construction excavations related to air raid shelter. The mosaic is spectacular.
privet