SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '021e4297c861301df21280177553f83748d49ce0fb78fa920141e678750d6c58' 
  AND token = 'drX06FkCfqQt1ulOLIPoAwYfpd9T5ex1LdgpbPQwmto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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