SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ba78633e03061fa075e34a15eef93f5fad8a22997be83f50eae1eb4f3aff6096' 
  AND token = 'zn8iF30kgSw9nY3gqqeew6iYJNAMmqrco6PhYggC10U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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