SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '00d4ed633465578888660b181d90c0449b93fdc8caad04c390a6e89248d3edc6' 
  AND token = 'FmYNQVNDIlx6OqmtysDwBS2HYrDZyVwtylMED4nrbgc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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