SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec0f8c0292975058165a138739184437fb038afc514e8da7f8cbf4f2205ee695' 
  AND token = 'nPVgmyiFlXsXkGRLk1Gq9WGn+vlFsufcVh0Vuf68OJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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