SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    12556, 12561, 12572, 12583, 12591, 12582, 
    12590, 12571, 12632, 12559, 12631, 
    10596, 10597, 10598, 10599, 10600, 
    10521, 10520, 10519, 10518
  )

Query time 0.00118

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 (12556,12561,12572,12583,12591,12582,12590,12571,12632,12559,12631,10596,10597,10598,10599,10600,10521,10520,10519,10518)"
    }
  }
}