‘orderby’ => ‘rand’ alternative for better performance?

I have been told that using this in the array:

'orderby'  => 'rand' 

will cause this:

Ordering by random is extremely expensive to query, involving creating temporary database tables, and scans, as it has to copy the entire posts table, then randomly re-order the posts, then finally do the actual query on the new table before destroying it.

And I have been advised:

It’s much easier to ask for the first post that occurs after a random date.

Can anyone elaborate on this?

Is there an array code line that will do the above?

Any resource regarding this would be very appreciated.