SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc3898becd343129f5d842b2c21164ff6410e326b6808f6c9d16fdcad1571141' 
  AND token = '320YmqCqLoeosBUbaNqYOc5wgpwzHYkI47V41HlfSeA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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