SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3599b55f0dfc6b853330c3e770204d4fda4cde5f9cf536d3ebc7ffe7fd4b659' 
  AND token = '6Tvc10IKkAWRkeQo8vNSAYO+rbAdwqUURhMMvagwUYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}