SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '892681d43b2f26052227eafc0370f852b1eca3484b26882416408ea31cc98e80' 
  AND token = 'X0xcp0WF5D/7sMyPNasgPjHnwI0pxGsank7hKu5sSh4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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