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 (
    97737, 97738, 97739, 97740, 97741, 97742, 
    97778, 97779, 97780, 97781, 97782, 
    97790, 97791, 97792, 97793, 97794, 
    98002, 98003, 98004, 98005, 98006, 
    98007, 98008, 98009, 98010, 98011, 
    98012, 98013, 98014, 98015, 98016, 
    98017, 98018, 98019, 98020, 98021, 
    98022, 98023, 98831, 98832, 98833, 
    98834, 98835, 98836, 98837, 98838, 
    98839, 98840
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00099

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "21.63"
    },
    "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": 48,
      "rows_produced_per_join": 48,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "16.83",
        "eval_cost": "4.80",
        "prefix_cost": "21.63",
        "data_read_per_join": "183K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (97737,97738,97739,97740,97741,97742,97778,97779,97780,97781,97782,97790,97791,97792,97793,97794,98002,98003,98004,98005,98006,98007,98008,98009,98010,98011,98012,98013,98014,98015,98016,98017,98018,98019,98020,98021,98022,98023,98831,98832,98833,98834,98835,98836,98837,98838,98839,98840)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}