SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ba542f9360badfd8aea708cf962e825625c8a1c84d3e40f44ac222585f095f29' 
  AND token = 'sI9jZAwJmjWCIIUTFXhSSc/Ulz/fhiKi1TF/nHePnpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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