SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '568e7ed040c1da0b4789e16123d99cf664b22210df596def8372b802da13035d' 
  AND token = 'zbHuHyCqN9LGW5e1yXBEzVJ1nAsrhp8vNpvljnN2Eng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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