Speed and size with hidden index in postgresql
Computers are fast and 1,000,000 is no longer a very large number.

Also, our query plan cut off the last line, Execution time:.  In my hands, it takes around 40ms to scan 1,000,000 rows with a parallel seq scan.  This is instantaneous in human terms, but is still 500 times longer than the planning time which you are (perhaps) confusing it with.