Select slow

I have two tables - one with around 80,000 rows(27 fields) and the other with 65,000 rows(2 fields).
When I do a simple select which involves a join, the database hangs. Show processlist displays the status as ‘sending data’ - this stage exists for indefinite time.

Select count(tbl1.tbl1_id) from tbl1,tbl2 where tbl1.tbl1_id = tbl2.foreign_key

Each of the tables have a primary key and no other index.

What may I do to make the joins faster.

Have you tried defining an index on “tbl2.foreign_key”