SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6858fe217a929cc76f3a841ead35ca893640ca0e44edfd650a942902194fcdc5' 
  AND token = '2dS5L5kd6s86dahRlpcwC8wavm2ITyoiMHfLjbEGDCU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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