code: protected function releaseLock($name)
      {
          return $this->db->useMaster(function ($db) use ($name) {
              /** @var \yii\db\Connection $db */
              return (bool) $db->createCommand(
                  'SELECT RELEASE_LOCK(:name)',
                  [':name' => $this->hashLockName($name)]
              )->queryScalar();
          });
      }
docs: Releases lock by given name.
  @param string $name of the lock to be released.
  @return bool release result.
  @see http://dev.mysql.com/doc/refman/5.0/en/miscellaneous-functions.html#function_release-lock