SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.short_description, 
  IF(
    cscart_product_descriptions.short_description = '' 
    OR cscart_product_descriptions.short_description IS NULL, 
    cscart_product_descriptions.full_description, 
    ''
  ) AS full_description 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    92971, 92972, 92973, 92974, 92975, 92976, 
    92977, 92978, 92979, 92980, 92981, 
    92982, 92983, 92984, 92985, 92986, 
    92987, 92988, 92989, 92990, 92991, 
    92992, 92993, 92994, 92995, 92996, 
    92997, 92998, 92999, 93000
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00086

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.52"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 30,
      "rows_produced_per_join": 30,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "10.52",
        "eval_cost": "3.00",
        "prefix_cost": "13.52",
        "data_read_per_join": "114K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (92971,92972,92973,92974,92975,92976,92977,92978,92979,92980,92981,92982,92983,92984,92985,92986,92987,92988,92989,92990,92991,92992,92993,92994,92995,92996,92997,92998,92999,93000)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
92971
92972
92973
92974
92975
92976
92977
92978
92979
92980
92981
92982
92983
92984
92985
92986
92987
92988
92989
92990
92991
92992
92993
92994
92995
92996
92997
92998
92999
93000