Sandbox

SELECT 
  1 
FROM 
  cscart_june_setupec_print_temp_designs 
WHERE 
  session_id = '6PH1-DC6S-YQ38-F4QQ-1L7A-UOLQ-6GE3-OKRA' 
  AND product_id = 135 
  AND expires_at > 1781896493 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00054

JSON explain

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