SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'def98b369c22e80050f33dc41a6c65005add0b347ae4a083360053ab5efdc0a1' 
  AND token = '1PrfXfC71qBAZpHS+oyqIYc1I0F+xVR/hyBq8Wj8d+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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