SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67920c34b1175f1fa31044e890d1f428ddd2601e253a2e40ff46dac37e2ddc3f' 
  AND token = 'txmNp9lN+esCz3KUrSGbFzuIFozDVQocxLUQO8XeoDY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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