SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b81e1ae5348d608f4f61a15a894d953603cdacf70be18aeaf102ea7a2277bf5b' 
  AND token = 'A3Votb9uPqqMTFwlLBWJMZI4j6tViP37XTR/lJM0hUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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