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 (
    264945, 264756, 264208, 263981, 264156, 
    264888, 264304, 264851, 264940, 264973, 
    264893, 264909, 264950, 264219, 264102, 
    264193, 264922, 264964, 264705, 366828, 
    366833, 371861, 366771, 371848, 371878, 
    366815, 264824, 371873, 366690, 263925, 
    264226, 371890, 264955, 371884, 263720, 
    371868, 366760, 366765, 371898, 264931, 
    371895, 366821, 366796, 371936, 371902, 
    377755, 371912, 372021, 377735, 371984, 
    371917, 371905, 366754, 366841, 371945, 
    371843, 371941, 371988, 371909, 371947, 
    366701, 371929, 371933, 371944, 371949, 
    371935, 371940, 381639, 185269
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00259

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "96.73"
    },
    "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": 69,
      "rows_produced_per_join": 69,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "82.93",
        "eval_cost": "13.80",
        "prefix_cost": "96.73",
        "data_read_per_join": "471K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`webmarco`.`cscart_product_descriptions`.`product_id` in (264945,264756,264208,263981,264156,264888,264304,264851,264940,264973,264893,264909,264950,264219,264102,264193,264922,264964,264705,366828,366833,371861,366771,371848,371878,366815,264824,371873,366690,263925,264226,371890,264955,371884,263720,371868,366760,366765,371898,264931,371895,366821,366796,371936,371902,377755,371912,372021,377735,371984,371917,371905,366754,366841,371945,371843,371941,371988,371909,371947,366701,371929,371933,371944,371949,371935,371940,381639,185269)) and (`webmarco`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}