CREATE TABLE `users` (
    `id`        INT(11) NOT NULL AUTO_INCREMENT,
    `name`  VARCHAR(255) DEFAULT NULL,
    `gender`    INT(11) NOT NULL COMMENT '0 - не указан, 1 - мужчина, 2 - женщина.',
    `birth_date`    INT(11) NOT NULL COMMENT 'Дата в unixtime.',
    `phone` VARCHAR(255) DEFAULT NULL,
    PRIMARY KEY (`id`)
);

SELECT name where  floor( datediff(curdate(), FROM_UNIXTIME(birth_date))/365 ) > 18 and  floor( datediff(curdate(), FROM_UNIXTIME(birth_date))/365 ) < 22 FROM `users`