SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cce5887bca3ac83fa73764a9df337829ea9a8df9e270dd018d27d745bef04f38' 
  AND token = 'ZHcHkXbLvvjxhOOc2YItkfinStNzgYSS8xfjBubWQOo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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