SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54edbe9367dd550b74231f69e07e9c6f33ff2409cef2490d48ab2cff72b84b35' 
  AND token = '+RGIPhO1/gh3rwdjKIKgIVhBmqw8sZWhTDOydWfC5N8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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