SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2b7b818e22bd33a308f9afc7d12184a9ab9243ce118dab966a9d1ca50485781' 
  AND token = 'a3FwsON/THohs5FIyw9SBCAkNg1W0LafVrgqmNZP/kU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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