SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df3b06843833af4bba66843ab97ad845732c2d36826f03ed4cf585a472636795' 
  AND token = '6nJsGjL7t9CeH/TcKYtQxDhUVPXz1yqK348nR9w9Yag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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