how to receive fast result from access query?

i have table (MyTbl) that has 3 field's A,B,C

this table contain 800000 records.

what is the best way to receive fast result ?

i try this:

select top 1 A from MyTbl where A='123'

but it isn't fast

i work with Access 2007 - and C# program

Create an index on the column A in MyTbl.

Create an index on table MyTbl, field A.