SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c57be1fdafc9c86da5cfa13a7d1321d0d6516883316e97bbfc5206e5d4891aad' 
  AND token = '+KhnsP4DSY6v8mjagkNItKO7TfPVLnINgcBgQH+VJPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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