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 (
    92712, 92713, 92714, 92715, 92716, 92717, 
    92718, 92719, 92720, 92721, 92722, 
    92723, 92724, 92725, 92726, 92727, 
    92728, 92729, 92730, 92731, 92732, 
    92733, 92734, 92741, 92742, 92743, 
    92744, 92745, 92746, 92747
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00094

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.52"
    },
    "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": 30,
      "rows_produced_per_join": 30,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "10.52",
        "eval_cost": "3.00",
        "prefix_cost": "13.52",
        "data_read_per_join": "114K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (92712,92713,92714,92715,92716,92717,92718,92719,92720,92721,92722,92723,92724,92725,92726,92727,92728,92729,92730,92731,92732,92733,92734,92741,92742,92743,92744,92745,92746,92747)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
92712
92713
92714
92715
92716
92717
92718
92719
92720
92721
92722
92723
92724
92725
92726
92727
92728
92729
92730
92731
92732
92733
92734
92741
92742
92743
92744
92745
92746
92747