SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9d57bc3197154b143d7ef8afaee96b8339e368a5d1e66c3308ce91191fba084' 
  AND token = 'Qh+ARRzom3c+ZbHFzKsZrf4uwDgjQ3Z2Wl/eGfNJ3jE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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