SELECT 
  1 
FROM 
  cscart_aprilec_print_temp_designs 
WHERE 
  session_id = 'FPNA-ME28-MCM8-MYDG-22KG-85TA-6P6U-Y02M' 
  AND product_id = 175 
  AND expires_at > 1777643513 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00025

JSON explain

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