SELECT 
  usergroup_ids 
FROM 
  cscart_pages 
  INNER JOIN cscart_ult_objects_sharing ON (
    cscart_ult_objects_sharing.share_object_id = cscart_pages.page_id 
    AND cscart_ult_objects_sharing.share_company_id = 1 
    AND cscart_ult_objects_sharing.share_object_type = 'pages'
  ) 
WHERE 
  page_id = 23

Query time 0.00027

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_pages const PRIMARY PRIMARY 3 const 1
1 SIMPLE cscart_ult_objects_sharing const PRIMARY PRIMARY 159 const,const,const 1 Using index

Result

usergroup_ids
0