SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    10905, 10907, 10917, 10918, 10920, 10921, 
    10923, 10924, 10927, 10933, 10943, 
    10946, 10950, 10952, 10955, 10956
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00119

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "product_id", "idx_product_lang"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["product_id", "lang_code"],
      "rows": 16,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (10905,10907,10917,10918,10920,10921,10923,10924,10927,10933,10943,10946,10950,10952,10955,10956) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}