SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3367013ee2196c647bedc42ad3c685dcbe1903c93aa4e3990b4a9669d3dd9f7a' 
  AND token = '68XGi7IWhS8ay2RdIE7IMhWAaY39vNLJKwwJ2q88iZo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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