SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ddc99afeafea4df9f5ddfbaa488cc5b9e38534c6f3dffdfddcb12afd13e73dee' 
  AND token = 'AurABW7+gYdpUKRfU2T1qhwT+Z7su1tGbmohWPXjQ8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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