[ic] sql query slower than expected

[DB]

I'm running IC 5.4.2 with mysql. My products table includes several
brands, ands each has a unique value for the category field. One brand
(category=BRAND_A) has many more skus that the others, nearly 250,000.

I want to display the skus from BRAND_A and the following query does the
job, however it is much slower than I expected and I can see the
server's CPU load spike up while it is running.

I do have the category column indexed. Can someone tell me why this is
so slow? My server is a dual Xeon with 4GB of Ram. Is this query that
horribly inefficient?

[query
    type=list
    more=1
    ml=75
    sql=|
        SELECT  sku, description, comment, category
        FROM    products
        WHERE  category = 'BRAND_A'
|]

[no-match]Not Found<br>[/no-match]

[more-list]
Matches [matches] of [match-count] shown.<br>
[/more-list]

[list]
<a href="[area [sql-code]]">[sql-param comment]</a><br> [sql-param
description]<br><br>
[/list]

[more-list]
Matches [matches] of [match-count] shown.<br>
[more]
[/more-list]
[/query]

Thanks for any thoughts.

DB