SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '193d581c4ad980449e298e02872197572eba95b74b53c6b1ac39d54995b420fe' 
  AND token = '6NAkTU7ZSlLT7VwWz6EhcYlOykAr2Z7hvoIUv10IwBQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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