select SQL_CALC_FOUND_ROWS 
`c`.*, 
`f`.`product_id` is not null as `fav` 
from `catalog` as `c` left join `favorite` as `f` 
on `f`.`product_id`=`c`.`id` and `f`.`user_id`=0 
order by `c`.`id` desc 
limit 0,32;

CREATE TABLE `favorite` (
 `id` int(12) unsigned NOT NULL AUTO_INCREMENT,
 `product_id` int(12) unsigned NOT NULL,
 `user_id` int(12) unsigned NOT NULL,
 `created` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
 PRIMARY KEY (`id`),
 KEY `product_id` (`product_id`)
) ENGINE=MyISAM AUTO_INCREMENT=36 DEFAULT CHARSET=utf8

CREATE TABLE `catalog` (
 `id` int(12) unsigned NOT NULL AUTO_INCREMENT,
 `pid` int(12) unsigned NOT NULL,
---
--- специфика поскипана
---
 PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=25084 DEFAULT CHARSET=utf8

select SQL_CALC_FOUND_ROWS `c`.*, `f`.`product_id` is not null as `fav` 
from `catalog` as `c` 
left join `favorite` as `f` force index for join(`product_id`) 
on `f`.`product_id`=`c`.`id` and `f`.`user_id`=0 
order by `c`.`id` desc limit 0,36;