SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37337de2536bf529f9974fecd56a947078c16066090bf07de36d865f8e553e34' 
  AND token = '1IiFr9moJhd4LjM+JIwysAgmtZ/UKPf0cdML8ZNf0HM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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