SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2cd913f31f794fc008ff2859b3793673e68bd89cf1eb6cdd156409833566d596' 
  AND token = 'bAojqvS18VR88bq7gWUG9S4EQ1PZUGMS1VtIUdQdoDI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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