SELECT 
  1 
FROM 
  cscart_aprilec_print_temp_designs 
WHERE 
  session_id = '7O81-S0AT-JR1R-7T7R-DDQW-YKI4-P753-TQ4O' 
  AND product_id = 36 
  AND expires_at > 1777128661 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00020

JSON explain

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