SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3743f61d38bba5835b0ac1d0be1b8cf406ab737d622e07df6caa677d789527a' 
  AND token = 'DD+dE7Wn9ygDwfL5oiYO2wf+jAjDQKTVl7sppHEfJt0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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