Found this at a Gulf Coast flea market and thought I would try to find out any information about the key.
There is a lot of info out there, but the only thing turned up was: "Rock Island is a neighborhood in Fort Lauderdale, Florida with a population of 5,095. Rock Island is in Broward County. Living in Rock Island offers residents a sparse suburban feel and most residents own their homes. In Rock Island there are a lot of parks.
If you collect these type keys, it's for sale...make an offer.