SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    64821, 64822, 64823, 64861, 64857, 64858, 
    65558, 65616, 65697
  )

Query time 0.00066

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_products",
      "access_type": "range",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 9,
      "filtered": 100,
      "attached_condition": "cscart_products.product_id in (64821,64822,64823,64861,64857,64858,65558,65616,65697)"
    }
  }
}

Result