select user_id from users where md5(concat(username, password)) = 'TOKEN_HERE'

string authHeader = application.Request.Headers["Authorization"];
        if (authHeader.ToUpper().Contains("BASIC"))
        {
            //get the user's name/password
            string decodedResponseString = Encoding.Default.GetString(Convert.FromBase64String(authHeader.Substring(6)));
            int dividerIndex = decodedResponseString.IndexOf(':');
            userName = decodedResponseString.Substring(0, dividerIndex);
            password = decodedResponseString.Substring(dividerIndex + 1);