SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ddaf246f696f3af81b98f74cdd4f3431732e98a291227a05ec4b352a1816f1ae' 
  AND token = '/BQm5XH6xbebOQiXJ7hTouRq7egQ5Y+zhOvUvIesxyQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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