SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd10729fdc399d1cc30d2db6f99dc55a26f6200aae374888e9a6deba051b3634' 
  AND token = 'gbfCNy9KPbpfDkSXhDzDZw3TpJwhHabFQr0ZvVffPcA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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