SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21888668e6e94a1c76bb51b94d92e48592aea0be6459823a8af1429bfbcc3b97' 
  AND token = 'JeObhzPusHRMrj2jTkH25ZS4a5nDwtxnmCy3qlXUJ5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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