SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7997e341d1df5f5932b6de6bf88a281b705e64801c505ddc3a8ee94526f9969' 
  AND token = 'sE+IpsJ7ABjp/JOzyCR4FBWNoDZ2lv/l7KUYPDmh+2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}