SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '151f3fd590041287b1546b0639155384167c88d39e1313f8eb54030e1a7d21f8' 
  AND token = 'MX2YnlD9EtxHF7b7KdYm3w6Kg8zek9HZcXWJmyKZVCU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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