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 (
    84640, 84641, 84508, 84509, 84574, 84575, 
    84638, 84639, 84636, 84637, 84506, 
    84507, 84572, 84573, 84661, 84662, 
    84504, 84505, 84570, 84571, 84634, 
    84635, 84310, 84311, 84502, 84503, 
    84568, 84569, 84529, 84530, 84595, 
    84596, 84665, 84666, 84533, 84534, 
    84599, 84600, 84306, 84307, 84308, 
    84309, 84519, 84331, 84332, 84304, 
    84305, 84632, 84633, 84681, 84682, 
    84685, 84686, 84679, 84680, 84683, 
    84684, 84622, 84623, 84500, 84501, 
    84566, 84567, 84549, 84550, 84553, 
    84554, 84615, 84616, 84619, 84620, 
    84652, 84653, 84547, 84548, 84551, 
    84552, 84613, 84614, 84617, 84618, 
    84335, 84336, 84490, 84491, 84556, 
    84557, 84520, 84521, 84586, 84587, 
    84663, 84664, 84302, 84303, 84351
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00203

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "43.24"
    },
    "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": 96,
      "rows_produced_per_join": 96,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "33.64",
        "eval_cost": "9.60",
        "prefix_cost": "43.24",
        "data_read_per_join": "366K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (84640,84641,84508,84509,84574,84575,84638,84639,84636,84637,84506,84507,84572,84573,84661,84662,84504,84505,84570,84571,84634,84635,84310,84311,84502,84503,84568,84569,84529,84530,84595,84596,84665,84666,84533,84534,84599,84600,84306,84307,84308,84309,84519,84331,84332,84304,84305,84632,84633,84681,84682,84685,84686,84679,84680,84683,84684,84622,84623,84500,84501,84566,84567,84549,84550,84553,84554,84615,84616,84619,84620,84652,84653,84547,84548,84551,84552,84613,84614,84617,84618,84335,84336,84490,84491,84556,84557,84520,84521,84586,84587,84663,84664,84302,84303,84351)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}