SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    20670, 22167, 22168, 21309, 22169, 21310, 
    22170, 21358, 21362, 21513, 22162, 
    22083, 22163, 21489, 22164, 20668, 
    22165, 20669, 22166, 21308
  )

Query time 0.00085

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_products",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "rows": 20,
          "filtered": 100,
          "index_condition": "cscart_products.product_id in (20670,22167,22168,21309,22169,21310,22170,21358,21362,21513,22162,22083,22163,21489,22164,20668,22165,20669,22166,21308)"
        }
      }
    ]
  }
}