only retrieving 1 row of data from MYSQL database

Answer 1

I am pretty sure that the query is ok. How many rows do you get with just

SELECT key_id FROM keyword

I think that there is just one line that matches your WHERE.

Answer 2

Check the query directly in the database(with phpmyadmin, or in the mysql console), however this query seems to be working as you may assumed. If it returns only 1 row when you use it directly in the db, then maybe there is only one row in your table wich matches this query.