Short story, I have this private key, but not sure at what crypto currency it belongs (surely not BTC/LTC) and I was wondering if there was a way to check if the private key belongs to a specific coin automatically without trying for each crypto
You can try with Pywallet or Findwallet, links are given in above topics.
(I saw that I can do it via GUARDA wallet, but it will take days).
Guarda is a close source wallet, and it's not good to use.