SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8512dd16f686b75cfa8f5bbfdbf61cd4434f05bdf05175f5328c998853d90c8' 
  AND token = '8KK4lluq6V2/K4jAqHLNFyy7pjLnTZDs2+YllJTa14g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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