SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    17198, 17199, 17200, 17201, 17202, 17203, 
    17204, 17205, 17206, 17207, 17208, 
    17209, 17210, 17211, 17212, 17213
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00257

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 (17198,17199,17200,17201,17202,17203,17204,17205,17206,17207,17208,17209,17210,17211,17212,17213) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}