SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64e8ceadd19656a756982fabec1013da7c2e9bccc3393e62dfc446e091709ee6' 
  AND token = 'vjxgMhbYJznk33fMy+f105dIRtsUh3vjXdRB6sR6tRk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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