SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d7246a9b6212b34dfe81b9e90ada397eacb435c8ec06b683ec58802a2463640' 
  AND token = '6M+xnFapi1udk8DLwi6mitn74NpzGIkEutd4JTQSDoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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