SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c844e0159f06f3496b6567c6ce509ade5add87931993f9bd0430b200f245f775' 
  AND token = 'ui9QSGoKWLjcGtKy16XK/eDo/H1vbhpzJw8PIilxJFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}