SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb6441978b333969ae550eead0a5648453ce1551715acd2e1ea1867570427381' 
  AND token = 'nkSwjKLrcfTCzuq/O/8MezzFBISWLwAwyfVgrXdM0bg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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