SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    21103, 21923, 21924, 21925, 21926, 21927, 
    19923, 22995, 21272, 22669, 22118, 
    20488, 20489, 20490, 20491, 20492, 
    21888, 21887, 21886, 21885, 20911, 
    20912, 20913, 20915
  )

Query time 0.00078

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": 24,
          "filtered": 100,
          "index_condition": "cscart_products.product_id in (21103,21923,21924,21925,21926,21927,19923,22995,21272,22669,22118,20488,20489,20490,20491,20492,21888,21887,21886,21885,20911,20912,20913,20915)"
        }
      }
    ]
  }
}