He was India captain Rohit Sharma's opening partner in the home T20 series against Afghanistan earlier this year but his place looked under threat as he struggled for runs in the IPL
Chris Gayle managed only seven in his final World Cup appearance and Hope could also have gone early but Rashid Khan dropped a sitter when the batsman was on five.
Lewis made 58 on his return to the side while Pooran's 58 was his third 50-plus score in the tournament.
Captain Jason Holder clobbered four sixes in his 45 off 34 balls and Dawlat Zadran claimed 2-73 for Afghanistan who were sloppy on the field.
Twice world champions West Indies have managed only one win in the tournament while Afghanistan have lost all eight games.