SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9b78c3cbfcd66d96abe56c39d5366d2c419f0460becf3ce8273ca78f2bcb9eb' 
  AND token = 'ohjrxeBcPAefajj6MtUqNKQpVhBIoVRbiJuKH59QyHc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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