SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29b35f1f52e232064207b472a4e46d37fa9285ab421ffd8927a8c4fc8db5474e' 
  AND token = 'OBzZPz7YqPJu0WthOHUi+Cqf/8pr3n1LzX8m2MVYGJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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