SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4327f936a6625d271c1cf21ac78e76b3d218a3d85e5000f030075e1ad734868' 
  AND token = 'Szi3wk2+Hc0rVKfLb+F4yZlrAeWxR8nDM7KJKafc7kA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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