SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '721418f09dac535df22415ffb3797fe6a8118614a9bfb8f4ed6de77a6c45a603' 
  AND token = 'Vq13J+UldjyaE1fm+P/WNqObLkWd/AZ+xfK18EaymRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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