SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af24c6767a460396ff39b6b5450d417b08741210c90a45826c514949bef23c66' 
  AND token = 'eNzlRRQYruAKSayj7Knv+PiEgqLgjBauXjc1easWyqc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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