SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'adbc408b59f6b3d17eb40b3a36e8a87a5cb6ddf176d569f9b013245ba1a1a6b8' 
  AND token = 'QkExyVJd8WJOGJm2xTv3QexIDoycr7dbkInztlZKsrY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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