Sandbox

SELECT 
  1 
FROM 
  cscart_aprilec_print_temp_designs 
WHERE 
  session_id = 'UDL8-JK6C-JK7H-Y4XQ-UJ0V-Y94T-5CRZ-NH78' 
  AND product_id = 123 
  AND expires_at > 1778166138 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00032

JSON explain

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