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 (
    90094, 90104, 90113, 91937, 91939, 91940, 
    91941, 91942, 91943, 89201, 89271, 
    89274, 89358, 91288, 86822, 86856, 
    83116, 83126, 83135, 89327, 91283, 
    83144, 90121, 89373, 89266, 82386, 
    84123, 86228, 89200, 89328, 86223, 
    89004, 89329, 91961, 91962, 91963, 
    91964, 91965, 91966, 91967, 83143, 
    89269, 86227, 84122, 82447, 89402, 
    89404, 91284
  ) 
  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 (90094,90104,90113,91937,91939,91940,91941,91942,91943,89201,89271,89274,89358,91288,86822,86856,83116,83126,83135,89327,91283,83144,90121,89373,89266,82386,84123,86228,89200,89328,86223,89004,89329,91961,91962,91963,91964,91965,91966,91967,83143,89269,86227,84122,82447,89402,89404,91284)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}