SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8eacc27f74afc2ee53151e72f177c7546bae84b4b353aecb7c401265d215d3c1' 
  AND token = '8jv72jI+5ls06NHeIkg1NGjYyQxXJWytTo0kSQpOThM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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