How to do Query Optimization in MySQL?

[messi]

SELECT scat.subcatid, scat.catid, COUNT(*) as adcnt
FROM xzclf_ads a USE INDEX (adsIndex)
INNER JOIN xzclf_subcats scat USE INDEX (subcatsIndex) ON scat.subcatid = a.subcatid AND (a.enabled = '1' AND a.verified = '1' AND a.expireson >= NOW())
INNER JOIN xzclf_cats cat USE INDEX(catidIndex) ON cat.catid = scat.catid
INNER JOIN xzclf_cities ct USE INDEX(cityidIndex) ON a.cityid = ct.cityid
WHERE scat.enabled = '1'
AND ct.countryid = 1
GROUP BY a.subcatid;
Could some one optimize this query. This query is taking more time to execute.