SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '338c17d68bc118669ac38de99c0366f2ff8c5c06c248615bc4bad12959e21f16' 
  AND token = 'kMrkLlcvjjKho6u+vm9cYA5ppnf1gf1dJnAGs+tPD6A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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