Query optimization question

[Nino Skilj]

Hi! I've been working on optimizing our database and have set up a few logs and optimized several queries. I turned on slow_logs and have just two that take a really long time. One really has me stumped... Any ideas?

I ran the following on my slow query (that takes up to 15 seconds):
-> explain SELECT SUM(Hours) AS totalHours
-> FROM hourstable
-> JOIN userstable ON userstable.id = hourstable.userid
-> WHERE userstable.companyid = '1234'
-> AND hourstable.paid = 0
-> AND userstable.status = 1
-> AND hourstable.timer = 1;

The explain result shows the following:
+----+-------------+---------+--------+----------------------------------------+---------------+---------+--------------------------------+------+-----------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------+--------+----------------------------------------+---------------+---------+--------------------------------+------+-----------------------------------+
| 1 | SIMPLE | hourstable | ref | ix_totalsum,ix_userid | ix_totalsum | 1 | const | 10 | Using where with pushed condition |
| 1 | SIMPLE | userstable | eq_ref | PRIMARY,ix_companystatus | PRIMARY | 4 | timeclock_alpha.hourstable.userid | 1 | Using where |
+----+-------------+---------+--------+----------------------------------------+---------------+---------+--------------------------------+------+-----------------------------------+


My question is... if it's only looking at 11 rows, why is it taking 15 seconds??? Am I missing something? Reading this information wrong? There are about 1.5 million records in the hourstable. Is that really making an impact on the query? I'm assuming I'm doing something wrong since I keep reading about people constantly handling 10+ million rows of data...

Any advice would be appreciated. Thanks in advance.

Nino