How can I remove rust from these old keys CAREFULLY?

I just dug up three old skeleton keys in my backyard. Skeleton keys are just a name for a simple type of key that can open pretty much any old typical lock back in the day. (I'm 15 years old). Anyways, i have the three keys, and they are just COVERED in thick rust. I'm almost thinking that they are just pure rust now. I want to find a way to get rid of the rust carefully and easily. Is there any way to do this without breaking the delicate keys? One was already chipping on the end of it.