SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5ca668ceb368f2675a3f9fa041ce123d4bc3fa046ffaa64fe98f554a8af0206b' 
  AND token = 'd+uF1F4n/yXFUEZ2vwCp8tTnQBuOZ38GNP6kRGa1ErU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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