As far as I can determine, the art was original for this production, rather than cribbed from a previously-published source. I've got to admit, Aparo wasn't at his best doing The Flash: the motion lines are a bit silly-looking, and the pose isn't nearly dynamic enough. But you know, posters like this played by different rules than, say, cover art. The important thing was giving a good look at the character and his costume, and conveying the premise of his powers. And the costume alone is so eye-catching that this makes for a pretty snappy-looking piece of art, especially at large size.
[In the comments, Scott detects that this is in fact recycled art, from Brave & Bold #151. How did I miss that all these years?]