SELECT 
  file_id, 
  filename, 
  filesize, 
  type 
FROM 
  cscart_cp_video_files 
WHERE 
  video_id = 58 
  AND lang_code = 'ru'

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_cp_video_files",
      "access_type": "system",
      "possible_keys": ["video_id"],
      "rows": 1,
      "filtered": 100
    }
  }
}