SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ffddb9ecd9ef14939f7add24a637edde2c68e76762286219550e69f2f52bc12' 
  AND token = 'j2Eg/gbvh9+AlU8DMbCmSBGoewS47Vmh9Qsvk8HRjeI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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