Yep, that's the Franklin Mint mintmark.

Actually, it's more than silver plated. The cladding process rolls 2 layers of silver onto the base metal (probably a nickel alloy) to make the sheet material that is punched to make the token planchet. I did a little more research and I believe the outer material is Sterling, probably several mills (thousandths of an inch) in thickness. The finished product has less silver than a solid sterling silver token, but more than a simple plated token would have. As with all silver, it will tone or tarnish with age if not in an airtight container.