SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b46b9f0469a9998cc5830bb89945e926e9d1c9a661e929fd8040caacc022ead' 
  AND token = '3SDZdx2saUvBdegQsTXnaVgBjabYnSIlHyyQVkyH3yU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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