SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '13a801f681257575b823383e303eb550d313f78854edac641a21acfb73a292c3' 
  AND token = 'XIfSKBsDHO23lVQOncaFOvxHfFZZ0rXst5EzcRgTquQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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