I tend to write an abstraction interface, if there isn't already one, where you request a key and pass an async function/lambda that will return the value from source in case of a cache miss.

    var value = cache.lookup<T>(
      keyname, 
      () => db.query<T>(...), 
      TimeSpan.FromMinutes(5) // or CacheOptions
    );

This way it can fallback/insert on a cache miss directly...