SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac959794ff583680ec778fa9c8a2529a147d6735640959732fcc4b986a5c81bb' 
  AND token = 'OMX0VMh5tPJ/vML3KngocMAr/B8hFWDigo4svAEQxzY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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