SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f2a8c77cac5670590eb78f186d4138b60f0ead458f843e9f174796568252d2b' 
  AND token = 'xlvFWAu/gZhcc6LK2daisJiFh9QR4nTb3jyLIodRHT8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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