SELECT
`certificates`.`id` AS `certificate_id`,
`certificates`.`name` AS `certificate_name`,
`dom_param`.`dom_id` AS `domain_id`,
`dom_param`.`val` AS `webmail_certificate_id`,
`Parameters`.`value` AS `mail_certificate_id`
FROM
`certificates`
STRAIGHT_JOIN `dom_param` ON
`dom_param`.`param` = "webmail_certificate_id" AND
`dom_param`.`val` = `certificates`.`id`
LEFT JOIN `Parameters` ON
`Parameters`.`parameter` = "mail_certificate_id" AND
`Parameters`.`value` = `certificates`.`id`
WHERE
`Parameters`.`value` IS NULL