SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b98963c55742a774478f77cf8e425533e5a378280610644c085f456ff49afa43' 
  AND token = 'yUpQCpxb0WsUiPzyygx2Bp7krg2J3NGfiNZPe2I2UX8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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