SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '621e1a5096680f83ec2a7bf242ca30e739b0ed0cf4bc04e31e2bd323126e8e30' 
  AND token = '9f4F41mOSaR+inkanwX/dLrBl9GRnwVbJvjP1rQM+Bg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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