SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68c42bae89e6487ef8028dc37e354d3e54a782aa544286517f8736407f8834c5' 
  AND token = 'b2vddfJ+gnoTYMes2nBghJ8YVRYDrtfpdPyeCuVTJ6E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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