SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6325f27889ef6a83136c97a65ba4087c11892d48bbe9189f600e3842f87a5360' 
  AND token = 'E52UloxMX902cn+oGFwobTG3o+CY31GhGh71fon3gWE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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