оптимизация запроса

Как оптимизировать запрос? записей больше 100 000, запрос занимает больше 30с

SELECT `product`.`id`, `product`.`name`, `product`.`condition`, `product`.`city_id`,  `product`.`price`,`user`.`name`  AS `user_name`, `city`.`name` AS `city_name`

FROM `product_to_category` `p2c`

JOIN `product` `product` ON product.id = p2c.product_id

LEFT JOIN `city` `city` ON city.id=product.city_id

LEFT JOIN `user` ON user.id=product.user_id

WHERE (

((`product`.`id` in (

					select product_id from product_to_city

					join city on (city.id = product_to_city.city_id)

					where city.id = 1 or city.parent_id = 1

				))) AND



( (`product`.`zombie` = 0)) AND (`product`.`publish` = 1 AND (`product`.`delete` = 0 OR `product`.`delete` is null)))

GROUP BY `product`.`id`

HAVING COUNT(1) > 1

ORDER BY `product`.`timestamp_update` DESC

таблица продукт

таблица city

таблица category

таблица product_to_category

таблица user

таблица product_to_city

explain