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 (
    94936, 94937, 94938, 94939, 94940, 94941, 
    94942, 94943, 94944, 94945, 94946, 
    94947, 94948, 94949, 95100, 95558, 
    95559, 95560, 95638, 95640, 95645, 
    95646, 95653, 95790, 95932, 95933, 
    95936, 95940, 96245, 96246
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00080

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 (94936,94937,94938,94939,94940,94941,94942,94943,94944,94945,94946,94947,94948,94949,95100,95558,95559,95560,95638,95640,95645,95646,95653,95790,95932,95933,95936,95940,96245,96246)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
94936
94937
94938
94939
94940
94941
94942
94943
94944
94945
94946
94947
94948
94949
95100
95558
95559
95560
95638
95640
95645
95646
95653
95790
95932
95933
95936
95940
96245
96246