CREATE TABLE album_photos
(
  photo_id int4 NOT NULL,
  participate_top bool DEFAULT true,
  views int4,
  sex int4 DEFAULT  0 ,
  ...
  CONSTRAINT album_photos_pkey PRIMARY KEY (photo_id)
) WITHOUT OIDS;

CREATE INDEX idx_top_views
  ON album_photos
  USING btree
  (views, sex) WHERE participate_top;

select photo_id from album_photos
where 
	participate_top and sex= 1 
order by views DESC
LIMIT  1 

Limit  (cost= 1 . 47 .. 1 . 48  rows= 1  width= 8 )
  ->  Sort  (cost= 1 . 47 .. 1 . 48  rows= 1  width= 8 )
        Sort Key: views
        ->  Seq Scan on album_photos  (cost= 0 . 00 .. 1 . 46  rows= 1  width= 8 )
              Filter: (participate_top AND (sex =  1 ))