SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5811df3e5ca359dc855f78cccd39c7fc7b73d35c31b6ba74f6e205ed1235e251' 
  AND token = 'DVSXqjHVywPXjtYOc7fpC9qC75GGKkuBkjJlTZFUAGY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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