SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e71c231aaaf0f6c0246565cd92f2afc040732df49ebed3e0865a741b2791959' 
  AND token = 'BiySjvWu58WL0ubRrhjPmPASTgKzvTXF+FXM9KUKPyo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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