SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    12974, 12975, 12976, 12977, 12978, 12979, 
    12980, 12981, 12971, 12983, 12984, 
    17670, 17671, 17672, 17673, 17674, 
    17675, 17676, 17677, 17678
  )

Query time 0.00127

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": 20,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (12974,12975,12976,12977,12978,12979,12980,12981,12971,12983,12984,17670,17671,17672,17673,17674,17675,17676,17677,17678)"
    }
  }
}