SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2bac0ec1337904dded1fbac78c9bb3e4e52a98ab497b46797a8ba812e5e8bc9' 
  AND token = 'L9z8knpduo7dgtS7PkKoHPdiH9BVTk1BWTFYwZOJBMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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