SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '10e8fbcac81f5a7831a8d9609a83bdfa4a872863eb35d31fed6ebd95bcead824' 
  AND token = 'KG0uT8Vy7mXLGBeXKAjN8eYHKwQ/1cXRw7mN8/DcN0Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}