SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '964e39df47ea67503d76d8326353989b67fce5c23e879c0e5bc2576c262908e3' 
  AND token = '/Kl3zjoKFdXyJm0GqB9DYzJN7jxrbfC0UF2xdZi1HlE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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