SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b0ed0b5e6762d074baeaeee75998ae2210fa2a7d41868331b9ed0cba138ffb8' 
  AND token = '3vGhNsCgQ1ZP1hDgPdLeCPgulgiQvNzCRfnrvjjlzKc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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