SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38ac5834e077d3b6dc119d50e73d4bf3dc123baf3a875fbb13e8135e55b04538' 
  AND token = 'bu5u06mMBpPtbdMdExYUCXNKPNIUlaG0ko4OEIdm8KE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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