SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b9ff51d3e9d745419b1cec1342ac45a71071d562a380ac3f1eb87972d78b739' 
  AND token = 'ICVmWrDllBtKiyvHZ/G8HQNZzhvwQNlBHO8zFZk4G+Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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