SELECT items.* FROM items i, meta_data m1, meta_data m2
WHERE i.item_id = m1.item_id and i.item_id = m2.item_id
AND m1.meta_key = 'lat' AND m1.meta_value >= 55 AND m1.meta_value <= 65
AND m2.meta_key = 'lng' AND m2.meta_value >= 20 AND m2.meta_value <= 30