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 (
    95, 96, 97, 100, 101, 102, 103, 104, 105, 
    106, 107, 108, 109, 110, 111, 112, 113, 
    114, 115, 116, 117, 118, 119, 120, 121, 
    122, 123, 124, 125, 127, 129, 131
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00479

JSON explain

{
  "query_block": {
    "select_id": 1,
    "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"],
          "rows": 32,
          "filtered": 100,
          "index_condition": "cscart_product_descriptions.product_id in (95,96,97,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,127,129,131) and cscart_product_descriptions.lang_code = 'ru'"
        }
      }
    ]
  }
}