SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8eca564c641b2464ca6cc79b3c72d820853f29b11f5e47a968d1ba5d450344d' 
  AND token = 'w7hznu34ICDq7hFGWfspKQp4yG2cshAjVe3Nims+/8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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