SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6c76ee2d8e7439a9e8c91d8302360113de1a3bf967f57dfb674716295005bf90' 
  AND token = 'IdicGujC8/0HAiwo6ih7qYvlEUYe8v1cE+B/2Q2TzFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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