The correct terminology would be Token Contract Address, not private key.
This may lead people to paste their private keys by mistake
More information here
What is a Token Contract Address?
If you've tried adding a new token to track for a wallet, one of the form fields asks you for a 'Token Contract Address'. This refers to the address location of the actual token contract that manages the logic for the tokens. This does not refer to the address that holds your own personal tokens!
To find out what this address is, we recommend looking at the token's website for more information or going on https://etherscan.io/tokens and searching directly for the name of your token!