SELECT  COUNT(DISTINCT p.product_id) AS total
FROM
  product p
  LEFT JOIN product_description pd ON (p.product_id = pd.product_id)
  LEFT JOIN product_to_store p2s ON (p.product_id = p2s.product_id)
  LEFT JOIN product_to_category p2c ON (p.product_id = p2c.product_id)
WHERE
  p.date_available <= '2014-10-13 13:00:00'
  AND pd.language_id = '3'
  AND p.status = '1'
  AND p2s.store_id = '0' AND (p2c.category_id = '327')

+----+-------------+-------+--------+-------------------------------+---------+---------+----------------------+-------+----------+--------------------------+
| id | select_type | table | type   | possible_keys                 | key     | key_len | ref                  | rows  | filtered | Extra                    |
+----+-------------+-------+--------+-------------------------------+---------+---------+----------------------+-------+----------+--------------------------+
|  1 | SIMPLE      | p     | ref    | PRIMARY,status,date_available | status  | 1       | const                | 30866 |   100.00 | Using where              |
|  1 | SIMPLE      | p2s   | eq_ref | PRIMARY                       | PRIMARY | 8       | p.product_id,const   |     1 |   100.00 | Using where; Using index |
|  1 | SIMPLE      | p2c   | eq_ref | PRIMARY                       | PRIMARY | 8       | p.product_id,const   |     1 |   100.00 | Using where; Using index |
|  1 | SIMPLE      | pd    | eq_ref | PRIMARY                       | PRIMARY | 8       | p2s.product_id,const |     1 |   100.00 | Using where; Using index |
+----+-------------+-------+--------+-------------------------------+---------+---------+----------------------+-------+----------+--------------------------+