SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0c2e9b88eda61332e62d2b48702be69be57f61d957280930d6691f2e59b288b' 
  AND token = 'yQJOACEJpOSg8IhKKPcgDkB7NhBdcBIH60bxm5rANuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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