Yeah, prefixing your keys with your service name like SRVCE_{KEY} is the way to go.
Bonus: adding SRVCE_PRVT_{KEY} and SRVCE_PUB_{KEY}.
Bonus: adding SRVCE_PRVT_{KEY} and SRVCE_PUB_{KEY}.
I also think that it should look just a bit cryptic to make a person unsure if they can meddle with the string.