SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '04c517893c73b824622a03cf0c5dfc157181a85a95ab609d9b834693ebe726ed' 
  AND token = 'fxPTl8XJ3hDoiMHYYnX+9AhrUow4QskPC5zbGzfKqqw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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