remove step and check existance of proper api key

lib/cartodb/api/auth_api.js

@@ -47,6 +47,13 @@ AuthApi.prototype.authorizedBySigner = function(res, callback) {
     });
 };
 
+function isValidApiKey(apikey) {
+    return apikey.type !== null &&
+        apikey.user !== null &&
+        apikey.databasePassword !== null &&
+        apikey.databaseRole !== null;
+}
+
 // Check if a request is authorized by api_key
 //
 // @param user
@@ -61,23 +68,19 @@ AuthApi.prototype.authorizedByAPIKey = function(user, req, callback) {
         givenKey = req.body.api_key || req.body.map_key;
     }
     if ( ! givenKey ) {
-        return callback(null, 0); // no api key, no authorization...
+        return callback(null, false); // no api key, no authorization...
     }
 
-    var self = this;
-
-    step(
-        function () {
-            self.metadataBackend.getUserMapKey(user, this);
-        },
-        function checkApiKey(err, val){
-            assert.ifError(err);
-            return val && givenKey === val;
-        },
-        function finish(err, authorized) {
-            callback(err, authorized);
+    this.metadataBackend.getApikey(user, givenKey, (err, apikey) => {
+        if (err) {
+            return callback(err);
         }
-    );
+        if ( !isValidApiKey(apikey)) {
+            return callback(null, false);
+        }
+
+        return callback(null, true);
+    });
 };
 
 /**