SELECT 
  1 
FROM 
  cscart_aprilec_print_temp_designs 
WHERE 
  session_id = '4O8I-DPX0-ILL5-8OYA-ZD2U-6L0G-ZM4E-0CMQ' 
  AND product_id = 69 
  AND expires_at > 1777644592 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00039

JSON explain

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