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 (
    95797, 95798, 95799, 95800, 95801, 95802, 
    95804, 95806, 95808, 95810, 95812, 
    96564, 96565, 96566, 96567, 96568, 
    97716, 97717, 97718, 97774, 97786, 
    98146, 98148, 98152, 98155, 98407, 
    98408, 98409, 98410, 98552
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00076

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 (95797,95798,95799,95800,95801,95802,95804,95806,95808,95810,95812,96564,96565,96566,96567,96568,97716,97717,97718,97774,97786,98146,98148,98152,98155,98407,98408,98409,98410,98552)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
95797
95798
95799
95800
95801
95802
95804
95806
95808
95810
95812
96564
96565
96566
96567
96568
97716
97717
97718
97774
97786
98146
98148
98152
98155
98407
98408
98409
98410
98552