SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fbad51e86ed8a41d713fed03e12d3e51f80b68a44f1ceae9325bd41741a6585' 
  AND token = 'HZnL7uDZP8v48/vG71XzIrs86Tnj6QpUDrRffgPyhcw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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