SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b416b5a52ab00755b7f1d288745374389c99f7631dff2d6616b3e5a4dc940570' 
  AND token = '/VvWv87s/PqYO97lq2Nr3ltkpAtJpkK14IGMtC9/nFs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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