SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a5e47df78974475e760db8baa0ba0d4d5b263c7635335fbeabd7d0f2968a4c9' 
  AND token = 'MDAnfWRKbDN3xD8EMKSzEoBCOkLXErrQJzdbSsrx8Gg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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