SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ecf95d469a81da7ad2d7d61fb91e44e2531b7bbd0db1a3b2abccf846c8e5852' 
  AND token = '/3cGDveiXuSb3XKk4uvCxPBncAOOfbTfsOwarjvG+AQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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