SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e21bb24dec991235c71aa57cfb568f4248846a5288e12769630033c6370e836' 
  AND token = 'vjhjk11tlE4CR0JjFq+95lYznTZb5hwksBKPA8ac89I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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