SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35003657241f8bf7fad1a52f13ed0de8094c784666bfb12673c3353d3a902eb2' 
  AND token = '2NgKHwxmsl95DH5QwXwnB7WgEhGCjERhlx45KvSrhjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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