SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '555b82998c34eb7998a226fea895b49bd0683ca09357fc41f249ed88c1d445b9' 
  AND token = 'YUNTW2taZyAV9NjXSGCSGQGhFTRk9qlIyHvp76lhwxQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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