chains are just a bunch of small bearings attached together .. Clearance on these bearings is precise. The rust you can see is not the problem. If the bearing are rusty no lube will help. Your owner's manual probably tells you to lay the chain out and measure it's length. A rusty worn chain will be longer than the limit specified.
A bad chain can and has killed people.. When they snap they wrap around the wheel and you do an unintentional panic stop but far more violently than those tiny brakes could ever hope to... and it can happen anywhere, anytime.
Get a new chain and keep it lubed so it never rusts. Motorcycle shops sell a variety of types of chain lube for different purposes.