SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26f8398b203aee4c0bddf8cbe8919650aae48cda8094dfc0954b292c7d069e2d' 
  AND token = '0So3d9SFKsNpT/jzlW+00ChjLEfOzOBhZIGNLzvqi6A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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