Thank you for your answer, David.
I am still not very familiar with the Iranian civic coppers. Since I bought a lot with several civic coppers, which did also include the fals of queen Rusudan, I have checked plenty of sites for civic coppers and indeed I didn't find one single coin that didn't have a formula on the reverse.
But I found this one with a very similar lion and a matching diameter and weight
http://numismatics.org/collection/1917.215.3042 plus the one illustrated in KM under A21 and another one which I failed to archive and can't find back now.
Of course I have no idea if this one has been struck as coin, token, medallion or something else and I am happy for any information that could help to solve the mystery.
I really came to like these coins and I am still very happy with my purchase.