mysql 쿼리 133개 불러오는데 1분... ㅠ.ㅜ

$sql = "

select c.ca_id, c.it_start, c.it_icon, c.it_id, c.it_name, c.it_id as pid, c.it_info1, c.it_info2, c.it_info3, it_icon, c.it_s_air, c.it_tour1, c.it_tour2,

a.prc_exchange, a.prc_halin, a.prc_price11, a.prc_price21, a.prc_price31,

(select CAST(prc_price11 AS UNSIGNED) AS LOWPRIC from wiz_prdprice where prc_price11>0 AND it_id = pid group by it_id order by LOWPRIC asc LIMIT 1) as price,

CASE a.prc_exchange

WHEN 'KOR'

THEN (select CAST(prc_price11 AS UNSIGNED) AS LOWPRIC from wiz_prdprice where prc_price11>0 AND it_id = pid group by it_id order by LOWPRIC asc LIMIT 1)

WHEN 'JPN'

THEN CAST((((select CAST(prc_price11 AS UNSIGNED) AS LOWPRIC from wiz_prdprice where prc_price11>0 AND it_id = pid group by it_id order by LOWPRIC asc LIMIT 1) 

* round((select ex_JPY1 from exchange order by ex_regdate DESC LIMIT 1)/100) ) * 100  ) AS UNSIGNED)

WHEN 'USD'

THEN CAST((((select CAST(prc_price11 AS UNSIGNED) AS LOWPRIC from wiz_prdprice where prc_price11>0 AND it_id = pid group by it_id order by LOWPRIC asc LIMIT 1)

* round((select ex_USD1 from exchange order by ex_regdate DESC LIMIT 1)/100) ) * 100) AS UNSIGNED)

WHEN 'CHN'

THEN CAST((((select CAST(prc_price11 AS UNSIGNED) AS LOWPRIC from wiz_prdprice where prc_price11>0 AND it_id = pid group by it_id order by LOWPRIC asc LIMIT 1)

* round((select ex_CNY1 from exchange order by ex_regdate DESC LIMIT 1)/100) ) * 100) AS UNSIGNED)

WHEN 'ERP'

THEN CAST((((select CAST(prc_price11 AS UNSIGNED) AS LOWPRIC from wiz_prdprice where prc_price11>0 AND it_id = pid group by it_id order by LOWPRIC asc LIMIT 1)

* round((select ex_EUR1 from exchange order by ex_regdate DESC LIMIT 1)/100) ) * 100) AS UNSIGNED)

END SUM

from wiz_prdprice as a, exchange as b, wiz_product2 as c

WHERE 1=1

AND c.it_id = a.it_id

AND a.prc_price11 > 0

AND it_use != 'N'

$catcode_sql

GROUP BY c.it_id

$order_sql

limit $start, $rows

"; 

위 쿼리를 돌리면 

133개 밖에 안되는 데이타를 가져오는데 1분 여 걸립니다.

이걸 최적화 하려면 어떻게 해야 할까요 ?

ㅠ.ㅜ