SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '451306765385287861b97551ce6cb7cfae3d62166fc26cff62e2d7cea8ee2389' 
  AND token = 'TSNeuPDCg/IprnfJiJlD8tpA4yW5LVCz6RQv1taMWBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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