SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd69be4a3f3633ea517fa32812748c0777bcc992e4e4175d99c826428ee70c92c' 
  AND token = 'fHlEujceCLNiTVTcxDNdjA0dJWySpGDpTOxntz4X7WE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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