SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b0ce02228733473b5c8806194725fd816984c5521af5f6aa6385993eed8e51f0' 
  AND token = 'P0JmNKPrAIiEJdqHRDbGPgo6sGxAjv457iGzcUtVdFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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