$ogr2ogr -f GeoJSON out.json "PG:host=localhost dbname=xxx user=xxx password=xxx"
 -sql 'select id, county, wkb_geometry from cities where id=47927526'

SELECT row_to_json(featcoll)
   FROM
    (SELECT 'FeatureCollection' As type, array_to_json(array_agg(feat)) As features
     FROM (SELECT 'Feature' As type,
        ST_AsGeoJSON(tbl.geom)::json As geometry,
       row_to_json((SELECT l FROM (SELECT id, prop1, prop2, ...) As l)
  ) As properties
  FROM your_table As tbL
   WHERE st_intersects(geom, st_setsrid(st_makebox2d(st_makepoint(x1, y1),st_makepoint(x2, y2)), srid))
 )  As feat
)  As featcoll;

$ogr2ogr -f GeoJSON out.json "PG:host=localhost dbname=xxx user=xxx password=xxx"
 -sql 'select id, county, wkb_geometry from cities where id=47927526'

$ogr2ogr -f GeoJSON out.json "PG:host=localhost dbname=xxx user=xxx password=xxx"
 -sql 'select id, county, wkb_geometry from cities where id IN (47927526, 47927527, 47927528, 47927529, ...)'