SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a9754b5d6b7fd02d70706e96d9f8cdabe9ed542025dcceea0eb759c3ba02581' 
  AND token = '5bzfXxuZ93cxnwJRxTiqYOO+FGCZd5KhPpDmlMua0Ak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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