This does not appear to be an active key mapping database. It looks to me to be a tool for the future for when the actual snapshot occurs. It has been used for the testnet. I would suggest following @sandwich 's instructions here (which are the same as on the official site https://eos.io/instructions) : https://steemit.com/eos/@sandwich/how-to-check-which-eos-public-key-is-mapped-to-your-eth-address-with-myetherwallet-mew