SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0006e8d8ae9536f0429dfcfabb8885f5b98b933c895cce1a4fb3d5f15c939af' 
  AND token = 'H+wRjw7Rzq/dXGxjQa9J7y0Uh1XmJc4u1yxwpAWq6KY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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