SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '00786bbe5b109413f05bab1e64acc9bb554f26bf1a2dc37ed1e9b2a1d687e690' 
  AND token = '9qPGyjsQj4KnebNqwNYlWyFFwXVzRvfg7RNeu9GI6+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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