SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b491fd7ad6e692aefe11c5d54ba0ee2a7916427c5846a81956322201a05b8f37' 
  AND token = 'HRchiV1UwMR0LOd5nl3utkqW+Ol/gtHM8JeLNyRmoBQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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