SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '208af2842f88db3d3b8a615056fde233a1fb5321004db8967b4af03b39b253d7' 
  AND token = 'YBKKQBgqFHdDTdIk+xRAguhVlapGVAbs+EEYWckDLs0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}