SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cb08ddc3716a9ef72e13d950226ee3e8aa92b4bb43bbdf524bc01affe9ff1d05' 
  AND token = 'IPiY+Y0NYzVfhHYke4CZJZPfJ3ZVvfyxLyhwnXCRn8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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