I am working on a web application that stores metadata about files in rocksdb, using their packed base64 MD5 hashes as a keys(Example: 7XDfSsHImTYaYDUIG8QfYg==) and allows end users to access it by providing same keys. Does rocksdb itself or its python-rocksdb API contain any vulnerability that would warrant sanitise those received key values before attempting to retrieve the data with them?
Does rocksdb itself or its python-rocksdb API contain any vulnerability that would warrant sanitise those received key values before attempting to retrieve the data with them?

There is no security risk in using rocksdb to store arbitrary data. The issues comes in when you are serializing / deserializing the value. You must use a known safe library.
Are there security security vulnerabilities in rocksdb or python-rocksd that warrant sanitizing keys received from external source?