SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a5fad5e5b56868dbae0f4d69005765dd3499bb8fb15b84bb5fe9d46f73f83c8' 
  AND token = 'gpRYmwLqd5+VMe2zAGB+Mx3sC2fXQ8kHYZvWmcCtMyE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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