SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e316121b84753a6b44d0d3fa5b1d5b7b5e03bc273f590e38483a6a2cadc1007' 
  AND token = '9L42VqL1ErHlY6qGaZKUoTrGo2mhL+BfEx6OCBqOyIE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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