SELECT 
  1 
FROM 
  cscart_ec_print_temp_designs 
WHERE 
  session_id = '9V3V-BV0H-AQ4L-D0CI-PNAM-HNPW-5CM2-W4K4' 
  AND product_id = 18 
  AND expires_at > 1770980879 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00048

JSON explain

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