SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2d6c706a27e4e674efee73a8d499597dd2abd5bfe01b75b3ac7a6cf7edb2410' 
  AND token = '6DvkRFnszr0Ta1nWWYKPSo0+K+38geXJ/4f9Y+V2YQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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