SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.meta_keywords, 
  cscart_product_descriptions.meta_description, 
  cscart_product_descriptions.search_words, 
  cscart_product_descriptions.promo_text 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    20586, 20645, 20647, 20646, 20635, 20648, 
    20636, 20649, 20637, 20650, 20638, 
    20639, 20640, 20641, 20643, 21515, 
    20644, 20188, 20331
  ) 
  AND cscart_product_descriptions.lang_code = 'uk'

Query time 0.00091

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": 19,
          "filtered": 100,
          "index_condition": "cscart_product_descriptions.product_id in (20586,20645,20647,20646,20635,20648,20636,20649,20637,20650,20638,20639,20640,20641,20643,21515,20644,20188,20331) and cscart_product_descriptions.lang_code = 'uk'"
        }
      }
    ]
  }
}