SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9729ba87193bfc61c892a79c0d81e0857bdde5b900c6d6899dc93290f3ddb61' 
  AND token = '9HmBS4ZIB8bjlRc2+/q3K81c2lSXyLl1V9GL7ZIhUS0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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