SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e704721891470ee965b3cc422551328ef1b7e8741fbc091918f8903e07f2f8b' 
  AND token = 'kRjuKqhlICyDq5nV2wko9lMB2v46rbdzYghCvnvshhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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