SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b18ee5e19827c1e9bf195ad17ab7d7efffcfe881168bbff054b4bd0c4fcf736' 
  AND token = '5rE7JJKxjR0/efCvJPbYKfsIIJiYiVlmzX23fxtfs8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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