SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    312879, 312875, 312878, 312836, 312880, 
    312865, 312874, 312868, 312849, 312850, 
    312877
  )

Query time 0.00049

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.01991781,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_products",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "loops": 1,
          "rows": 11,
          "cost": 0.01991781,
          "filtered": 100,
          "attached_condition": "cscart_products.product_id in (312879,312875,312878,312836,312880,312865,312874,312868,312849,312850,312877)"
        }
      }
    ]
  }
}