SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'def8933f03892050196c8682ca150ad1705f7c6d6f3c0a25cf03bc5574a9cfa4' 
  AND token = '4r/qEM1TldiVN4OlbJIOJaq8h4v7mQYw+yOFB+TPu/4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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