SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '502f3a997de5cb6a8b093d300f97914550701aa4994f0d2c5c65476322b9ccb9' 
  AND token = '2HuxjxVJxuAV4nOxdvqo5Bd68NcAD4xGdFmAGGbKVa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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