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, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    99, 97, 98, 91, 96, 182, 451, 454, 453, 
    457, 701, 702, 708, 228, 452, 447, 829, 
    831, 818, 774, 823, 833, 368, 432, 433, 
    434, 435, 436, 437, 438, 439, 440, 441, 
    442, 443, 444, 445, 446, 369, 417, 418, 
    419, 420, 421, 422, 423, 424, 425, 426, 
    427, 428, 429, 430, 431, 367, 402, 403, 
    404, 405, 406, 407, 408, 409, 410, 411, 
    412, 413, 414, 415, 416
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00052

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.12250642,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_descriptions",
          "access_type": "range",
          "possible_keys": ["PRIMARY", "product_id"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["product_id", "lang_code"],
          "loops": 1,
          "rows": 70,
          "cost": 0.12250642,
          "filtered": 100,
          "attached_condition": "cscart_product_descriptions.product_id in (99,97,98,91,96,182,451,454,453,457,701,702,708,228,452,447,829,831,818,774,823,833,368,432,433,434,435,436,437,438,439,440,441,442,443,444,445,446,369,417,418,419,420,421,422,423,424,425,426,427,428,429,430,431,367,402,403,404,405,406,407,408,409,410,411,412,413,414,415,416) and cscart_product_descriptions.lang_code = 'en'"
        }
      }
    ]
  }
}