SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 
    92, 93, 94, 95, 96
  )

Query time 0.00076

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": 16,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96)"
    }
  }
}