SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b88157c42fb57495a2a3316b5a59019038fb942becd0766dfff8fe57064dbbe3' 
  AND token = 'GKnOWjwUgf/gMmGIrceuHC28B/bpjW40/+UbUjc4IZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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