SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '140e3c25bea92813fb45e515537bac4a11137d6dea612e6b6f50784662be9987' 
  AND token = 'XjMaQGwrN7UYb8PiSP6MkGOLs2dK3YTZu65RPceQkG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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