SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9e3fb0721519544ab1d1161fb3194c88837a88afbbd9c3ad6e182d9eb1f8857' 
  AND token = 'IR/soqoimXvC/+YFiGdhohK+FgVaRpvtgwVTxpcUIHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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