SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '296b0dc0dc17fef2d004bb20b811e9133947eb19f10abb186fee4a82b267ff3d' 
  AND token = 'qXsT9Fgbda9PM+h5PaETKQW1D17F0ijP5TcUnkIJJx8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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