SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35d1457875a1f45ba2160c901a5e1317b7e79debee3dc6605329bfeac8ebb281' 
  AND token = 'gDYRZDQzWHhq1K+Qz+BeelpkmKx2hFm75DUwLj0i3vI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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