What indexes should be added to the query?

Question

MySQL

Tell me what indexes need to be added to get rid of
Using filesort

The query itself

EXPLAIN EXTENDED 
SELECT 
  SQL_NO_CACHE DISTINCT BE.ID as ID 
FROM 
  b_iblock B 
  INNER JOIN b_lang L ON B.LID = L.LID 
  INNER JOIN b_iblock_element BE ON BE.IBLOCK_ID = B.ID 
  INNER JOIN b_iblock_7_index FC ON FC.ELEMENT_ID = BE.ID 
  LEFT JOIN b_catalog_product as PRD ON (PRD.ID = BE.ID) 
WHERE 
  1 = 1 
  AND (
    (
      FC.SECTION_ID = 2 
      AND FC.FACET_ID = 1 
      AND FC.VALUE_NUM = 0 
      AND FC.VALUE IN (0)
    ) 
    AND (BE.PREVIEW_PICTURE IS NOT NULL) 
    AND (
      EXISTS (
        SELECT 
          IBLOCK_ID 
        FROM 
          b_iblock_site 
        WHERE 
          IBLOCK_ID = B.ID 
          AND (SITE_ID = 's1')
      )
    ) 
    AND (
      (
        BE.ACTIVE_TO >= now() 
        OR BE.ACTIVE_TO IS NULL
      ) 
      AND (
        BE.ACTIVE_FROM <= now() 
        OR BE.ACTIVE_FROM IS NULL
      )
    ) 
    AND (BE.ACTIVE = 'Y') 
    AND (BE.IBLOCK_ID = '7')
  ) 
  AND (
    BE.WF_STATUS_ID = 1 
    AND BE.WF_PARENT_ELEMENT_ID IS NULL
  ) 
  AND (
    B.ID IN (
      SELECT 
        IBLOCK_ID 
      FROM 
        b_iblock_group IBG 
      WHERE 
        IBG.GROUP_ID IN (2) 
        AND IBG.PERMISSION >= 'R' 
        AND (
          IBG.PERMISSION = 'X' 
          OR B.ACTIVE = 'Y'
        )
    ) 
    OR (
      B.RIGHTS_MODE = 'E' 
      AND EXISTS (
        SELECT 
          ER.ELEMENT_ID 
        FROM 
          b_iblock_element_right ER 
          INNER JOIN b_iblock_right IBR ON IBR.ID = ER.RIGHT_ID 
          INNER JOIN b_user_access UA ON UA.ACCESS_CODE = IBR.GROUP_CODE 
          AND UA.USER_ID = 0 
        WHERE 
          ER.ELEMENT_ID = BE.ID 
          AND IBR.OP_EREAD = 'Y'
      )
    )
  ) 
ORDER BY 
  BE.ID DESC 
LIMIT 
  3

EXPLAIN


Extra tables BE

Answer 1

no index will help. need to reformulate the request