SELECT 
  1 
FROM 
  cscart_aprilec_print_temp_designs 
WHERE 
  session_id = 'BXBB-9FB0-D0U6-S65R-5S4I-CW54-IV1A-PX5N' 
  AND product_id = 8 
  AND expires_at > 1777915282 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}