SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9cc797fa5a9072dd2af6251bb8bb2e87e68646211d4e3c94ba884f7c77d20df' 
  AND token = 'RScuds6wx64QXhbEw4hJ18VQ5HY+7fIAII7TmG5XvJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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