SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6dde19c9387a9b46d1d044103cacda57eb9ec654a47308daae355752731515d' 
  AND token = '/pYOpVyNDw/a7IGJV/jcqrM8OwdW9p3YNJ4DVXLp3nk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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