SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c951e30a468857e5bd0d1ee31f9a5d9aa0c5ff8244ee0b01d28d0a9b2f376f05' 
  AND token = 'F6ta2ab3r//i8pR3mjIMZ/1qFodXNUveDp3NP6OhT3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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