SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e04b9f118cd21c8cdec8f3c1c3488bdee5453709c71cc6081b04f3786fb73758' 
  AND token = 'nc8fRycy1PYiJhncwZRHPmIWeoAcRrDdtUe0yAaLs5U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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