SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae321dcaadb3303feca5389b656c374b20dc5bc828f739a4e950eaac83ce3b32' 
  AND token = '71X1kOaqQkTvwU2UCJcdWeGDvs7j+j/Uh23XmVfFpmI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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