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 (
    97525, 97526, 97527, 97528, 97529, 97530, 
    97531, 97532, 97533, 99068, 99069, 
    99070, 99071, 99072, 99073, 99074, 
    99075, 99076, 99079, 99080, 99083, 
    99084, 99085, 99086, 99087, 99088, 
    99089, 99090, 99091, 99092
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00070

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 (97525,97526,97527,97528,97529,97530,97531,97532,97533,99068,99069,99070,99071,99072,99073,99074,99075,99076,99079,99080,99083,99084,99085,99086,99087,99088,99089,99090,99091,99092)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
97525
97526
97527
97528
97529
97530
97531
97532
97533
99068
99069
99070
99071
99072
99073
99074
99075
99076
99079
99080
99083
99084
99085
99086
99087
99088
99089
99090
99091
99092