SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '312bdd9ad3def498157c6b6dae4932a678355e5ae0cf415fba429c337451038e' 
  AND token = 'G6lGTCu/JQL81KR3hWhWFsvjRz9NY6oJ5CLhGJv/v0k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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