SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '709e0041afe408f1729dcb43b33b9281cd96cb959661cf4d64b9639b21d1b81c' 
  AND token = '4+wQYHuEYLX3fi/iF+UJ5KV2U8UMFP7YGeRzvKe8/Dk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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