after changing indexing on table it is working
CREATE TABLE IF NOT EXISTS `users` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`user_group_id` tinyint(3) unsigned NOT NULL DEFAULT '2',
`username` varchar(50) NOT NULL,
`email` varchar(80) NOT NULL,
`password` varchar(50) NOT NULL,
`first_name` varchar(25) DEFAULT NULL,
`last_name` varchar(25) DEFAULT NULL,
`gender` enum('m','f','u') NOT NULL DEFAULT 'u' COMMENT 'm=>Male, f=>Female, u=>Unspecified',
`profile_image` varchar(255) DEFAULT NULL,
`reset_key` varchar(50) DEFAULT NULL,
`modify_username` enum('0','1') DEFAULT '0',
`block` enum('y','n') NOT NULL DEFAULT 'n' COMMENT 'y=>blocked, n=>notblocked',
`status` enum('0','1') DEFAULT '0',
`created` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
`modified` timestamp NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (`id`),
UNIQUE KEY `id_username_email` (`id`,`username`,`email`),
KEY `username` (`username`)
KEY `email` (`email`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 CHECKSUM=1 DELAY_KEY_WRITE=1 ROW_FORMAT=DYNAMIC