SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a561c8edf27d74402fe10f644bd7d2d498ea8fadc1d3ba78143ab67fbc035665' 
  AND token = 'RLp+4cztJabVMYdYoFhWaFNOkYHY7svt1OP3auudyb0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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