SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c025896f645a85c39185eb34806e23113347702c633ca66eac7e079311e48b07' 
  AND token = '3luBAtUa+VduNCIUwNfh15mXUDXTcXoTvxIGVMf8eWc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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