SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0fb4580fe47676cbc88540b1b31a7a82bf44b19e40a3728fc9b9f4a5eefbc8a' 
  AND token = '3/f6/RzGTTj1ExdvQa/chIDkoqy2Az/ihMrRngWeUi0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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