SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1781b98bdb4184b0433311f803d3790f0056b87731976337f971ff1d52ed036e' 
  AND token = '0IYo+DLKZmqzwm1aVEFJ5wqZDEnCq+dCsrjIcAbEsO8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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