SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '370ad6e059a335baf24d74c52dc1ef8da5d30532a3853dacc69eef2dbc31b867' 
  AND token = '2qf/xkdMeKZokZ+IUHJQ3omRCyvbHYUWGs7fiqPrABI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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