Оптимизация запроса с использованием LEFT JOIN

`id` int(10) NOT NULL AUTO_INCREMENT,
  `dirname` varchar(1000) CHARACTER SET utf8 NOT NULL,
  `filename` varchar(1000) CHARACTER SET utf8 NOT NULL,
  `fileextension` varchar(10) CHARACTER SET utf8 NOT NULL,
  `filesize` double(20,1) NOT NULL,
  `filectime` datetime NOT NULL,
  `filemtime` datetime NOT NULL,
  PRIMARY KEY (`id`),
  FULLTEXT KEY `filename` (`filename`),
  FULLTEXT KEY `fileextension` (`fileextension`)

 `id` int(100) NOT NULL AUTO_INCREMENT,
  `connection_id` varchar(10) NOT NULL,
  `account_id` varchar(50) NOT NULL,
  `logname` varchar(100) NOT NULL,
  `ip` varchar(15) NOT NULL,
  `log_filename` varchar(1000) NOT NULL,
  `log_filename_ext` varchar(10) NOT NULL,
  `uplendtime` datetime NOT NULL,
  `sizelastlogin` double(10,2) NOT NULL,
  `uplspeed` int(10) NOT NULL,
  PRIMARY KEY (`id`),
  FULLTEXT KEY `log_filename` (`log_filename`),
  FULLTEXT KEY `log_filename_ext` (`log_filename_ext`)

SELECT * FROM `file` LEFT JOIN `connection` ON `file`.`filename` = `connection`.`log_filename` ORDER BY `file`.`filectime` DESC, `file`.`id` DESC LIMIT 50