SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '004d954bba1d1dcd462144122eb9c36238075b6b9408e73f86c07ba2f7b7bd93' 
  AND token = 'RcEZhRDNSAmMAq6bfN6CHhaPfJvVdKzDjRFveFvBPek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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