SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a3cfd4066e9751cf4a04c6beace35d68f73d2318b60814cf0d55f331b5e7ec9' 
  AND token = 'BSwoi1j7ow/4AwEWdXZgI977zPE1Zuhbvwl0YusFHtg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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