SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f6921127d619b6288da6b9e9c1e794424fa3318224a9419a449999ccee0259b' 
  AND token = 'FwIdXqIQ9cB0pDbztl+N4ONSwlMNM7wuY0A090GsGMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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