SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9d57cbbefbc8ddd1d993e633d3ed9c08c6f85130adf67831adaeb7abd46fc8e' 
  AND token = 'XlaRZMS0aoz1f/+tNvKQLhocmjSneE9qvdyDdwNsPmo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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