Query planner question

select t.ticket_id ,

tb.transmission_id

from ticket t,

transmission_base tb

where t.latest_transmission_id = tb.transmission_id

and t.ticket_number = tb.ticket_number

and tb.parse_date > ('2014-07-31');

Execution plan: http://explain.depesz.com/s/YAak

Indexes on ticket :

This query only returns some portions of rows from ticket table.

The question is, Why does postgres need to get all the rows from ticket table in order to complete this query?

Can't postgres use indexes to get only needed rows on ticket table?

I try set seqscan to off, but still index scan try to get all rows on ticket table.

Here's the execution plan : http://explain.depesz.com/s/abH2

Thanks

Soni Maula Harriz