SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39982eaba23843e2a53d1237920f03fe86fcaaa7465ac85a516f926f4851a56f' 
  AND token = 'WtSW8X8jQcYkSTQq1OORRw6FuswulNqpgXUhqOPBlPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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