SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36ccbc16a5d75527ce149be5548d16fd5154c35f6de8cd506a0084dde5d32a35' 
  AND token = 'M1axBHb8CD5dWYcn5AQhjkTK8mYj7tw1JaiWMqvvVx4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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