SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8eee16be2aeb708264799374cef2692880465be0682eafaecf0108d3d6dccf21' 
  AND token = 'eaSuwbhdNES7RDp3WUF8fVjDOF1xau2o93udd96z/G0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00092

JSON explain

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