SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f0e2190d3604571900b1e9ff888fb55e7d98de0590e7f7560e8ba8a565b059c' 
  AND token = 'zUJ5wg7VBxIQ5yIlSgrn+T9rVIDkwfOwwjOPLXftblQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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