SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4875c85a01ab55df7eca4b6d3e0303be2f32910e57702c399b7b055053fd9abf' 
  AND token = 'OL7Y2sYPEkuCxx4Png+dATFryQMMAaFfNzomgzSuq+Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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