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 (
    96121, 96494, 96495, 96496, 96497, 96498, 
    96499, 96500, 96501, 96502, 96503, 
    96504, 96505, 96506, 96507, 96508, 
    96509, 96530, 96570, 96571, 96572, 
    96573, 97574, 97575, 97581, 97608, 
    97609, 97610, 97611, 97612, 97613, 
    97614, 97615, 97616, 97617, 97618, 
    97619, 97620, 97621, 97622, 97623, 
    97624, 97625, 97626, 97627, 97629, 
    97630, 97631
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00095

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 (96121,96494,96495,96496,96497,96498,96499,96500,96501,96502,96503,96504,96505,96506,96507,96508,96509,96530,96570,96571,96572,96573,97574,97575,97581,97608,97609,97610,97611,97612,97613,97614,97615,97616,97617,97618,97619,97620,97621,97622,97623,97624,97625,97626,97627,97629,97630,97631)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}