SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3b2394677f133009250cc5f306767c2a8c0dee29cee578c94e1e7be6fc4a65e' 
  AND token = 'NNXrg8DzGvobhWHu82MmwlsxPM7/IaHvP9qcKFkHhMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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