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 (
    356409, 350046, 354359, 356853, 352482, 
    353629, 354406, 355426, 355756, 359005, 
    353291, 353422, 353953, 353011, 354242, 
    352265, 353900, 354462, 355261, 350775, 
    353633, 354225, 351736, 354304, 355482, 
    356747, 351040, 354404, 351297, 355509, 
    356071, 349717, 355980, 353297, 352887, 
    357199, 351199, 352517, 352931, 355954, 
    356494, 357133, 357328, 357778, 352087, 
    352829, 354677, 356789, 357912, 350238, 
    354170, 351753, 354341, 355693, 356075, 
    358569, 351755, 352593, 353948, 350359, 
    355361, 356708, 350053, 351003, 353554, 
    353857, 357157, 354199, 353151, 353329, 
    353465, 358545, 351200, 353467, 354580, 
    355358, 358830, 350043, 351556, 355662, 
    354403, 351685, 356222, 358385, 350880, 
    350980, 352330, 352211, 350218, 351737, 
    354906, 356225, 357268, 352091, 354263, 
    355290, 349857, 355259, 357941, 358652
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00345

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "140.18"
    },
    "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": 100,
      "rows_produced_per_join": 100,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "120.18",
        "eval_cost": "20.00",
        "prefix_cost": "140.18",
        "data_read_per_join": "682K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`webmarco`.`cscart_product_descriptions`.`product_id` in (356409,350046,354359,356853,352482,353629,354406,355426,355756,359005,353291,353422,353953,353011,354242,352265,353900,354462,355261,350775,353633,354225,351736,354304,355482,356747,351040,354404,351297,355509,356071,349717,355980,353297,352887,357199,351199,352517,352931,355954,356494,357133,357328,357778,352087,352829,354677,356789,357912,350238,354170,351753,354341,355693,356075,358569,351755,352593,353948,350359,355361,356708,350053,351003,353554,353857,357157,354199,353151,353329,353465,358545,351200,353467,354580,355358,358830,350043,351556,355662,354403,351685,356222,358385,350880,350980,352330,352211,350218,351737,354906,356225,357268,352091,354263,355290,349857,355259,357941,358652)) and (`webmarco`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}