SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '588c607d911e3bab545250a5dd63260350875d1a6a9112e29e5bcd371875b4e2' 
  AND token = '17UYFXdz1ijPUcXk+JeLkDixZ2qiC/SDUM1QgWy7jqM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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