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SELECT 
  pair_id, 
  v.video_id, 
  video_url_id, 
  source, 
  position 
FROM 
  cscart_videos as v 
  INNER JOIN cscart_videos_links as vl ON v.video_id = vl.video_id 
WHERE 
  object_id = 221 
  AND vl.object_type = 'product' 
ORDER BY 
  position

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}