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 (
    339432, 339433, 339438, 339434, 339439, 
    339445, 262432, 339440, 339441, 264700, 
    339446, 339447, 339449, 339689, 339448, 
    339450, 339435, 339442, 339443, 339436, 
    339451, 339437, 339444, 339476, 339456, 
    339550, 339461, 339454, 339547, 339471, 
    339545, 339474, 339548, 339470, 339544, 
    339455, 339543, 339549, 339698, 339472, 
    339542, 339487, 339480, 339475, 339688, 
    339546, 339687, 339690, 339462, 339700, 
    339811, 339459, 339679, 339473, 339813, 
    339678, 339465, 339457, 339477, 339541, 
    339489, 339699, 339469, 339458, 339482, 
    339685, 339468, 339453, 339730, 339731, 
    339478, 339463, 339709, 339467, 339460, 
    339808, 339464, 339806, 339810, 339701, 
    339807, 339479, 339452, 339729, 339485, 
    339809, 339812, 339484, 339483, 339466, 
    339486, 339488, 339481
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00411

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "130.37"
    },
    "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": 93,
      "rows_produced_per_join": 93,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "111.77",
        "eval_cost": "18.60",
        "prefix_cost": "130.37",
        "data_read_per_join": "635K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`webmarco`.`cscart_product_descriptions`.`product_id` in (339432,339433,339438,339434,339439,339445,262432,339440,339441,264700,339446,339447,339449,339689,339448,339450,339435,339442,339443,339436,339451,339437,339444,339476,339456,339550,339461,339454,339547,339471,339545,339474,339548,339470,339544,339455,339543,339549,339698,339472,339542,339487,339480,339475,339688,339546,339687,339690,339462,339700,339811,339459,339679,339473,339813,339678,339465,339457,339477,339541,339489,339699,339469,339458,339482,339685,339468,339453,339730,339731,339478,339463,339709,339467,339460,339808,339464,339806,339810,339701,339807,339479,339452,339729,339485,339809,339812,339484,339483,339466,339486,339488,339481)) and (`webmarco`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}