SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8cf3a885b75ebf477c2588a9553b60f064dc804ec0e8d8f293829afe3acfde45' 
  AND token = '/wpZLr9t/KBfRiUv65B6sH/XOGohwBMMB4rYicYYzdY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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