explain analyze functionality

i have an SQL query of the general type

select att0 from table where 1 <= att0 and att0 < 1000000

to a table of the general format (att0 int4, att1 int4) where there is an
index on att0 and when i run the explain analyze on that question it
returns me the following result:

NOTICE: QUERY PLAN:

Index Scan using index1 on class y (cost=0.00..3662.16 rows=1266 width=4)
(actual time=0.44..4323.38 rows=1000000 loops=1)
Total runtime: 4563.40 msec

NOTICE: QUERY PLAN:

Index Scan using index1 on class y (cost=0.00..3662.16 rows=1266 width=4)
(actual time=0.44..4323.38 rows=1000000 loops=1)
Total runtime: 4563.40 msec

doews anyone know each of those two index scans, which are stated there
are unique to which of the two conditions refer: to condition 1 <= att0,
to condition att0 < 1000000 or to the union of those two questions? I
would appreciate any opinion, help.

SWTHRHS TOYRTOYNHS
(tourtoun(at)csd(dot)uch(dot)gr)