SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b6f744949305cbff50bbf4d8da2374e426985c3611cd5b96b9f884e0ac68bfe' 
  AND token = 'x8iFU6TJqFXjn6qXyUNoE+azzMVxAhFh7QdtSZ9Rhwg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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