foreach $key (@keys) {
  $sth->execute($key);
  $columns_ref = $sth->fetchrow_arrayref();
  push(@entries, [@$columns_ref]);
}

##</code><code>##

foreach $key (@keys) {
  $sth->execute($key);
  my $columns_ref = $sth->fetchrow_arrayref();
  push(@entries, $columns_ref);
}