SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7eec6350505c1a62df90605418fd9ffc77b09f1f122302c62b8fa4cafc838f66' 
  AND token = 'nd4afS6hOqV8lYxw3bUqttY8+NaUzCkZoBsj1VxQo6Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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