The rarity index is determined based on how many members have an item in their collection. For coins and banknotes it can sometimes give a rough idea of how common or uncommon an item is, but for tokens it's far less useful. In the latter case, it indicates an item that nobody really cares to collect rather than anything valuable. Your item is a good example of this. This is a token from a restaurant in Rome called the Blue Grotto (that is no longer at that location, it seems). Unless you find someone looking for memorabilia from that exact restaurant or a collector who looks for Italian restaurant tokens, it's worth the metal it's made of (practically nothing).