SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b91e48a891d241d9c41f8519c7650d8fccda9a9266f20bb0dcc8aebcbf96172' 
  AND token = 'rscKp4NAyVotF3DOiLqkNwqPXA7gQ64WlGAaWspKYN4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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