SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '78be755e877874714711e1336c85091390b38c97e242c7ca4fe44c333e7c2360' 
  AND token = 'AwlRqqYQ2LaNveTFcj4JOzpnVrP+lG0b9rXw+hkhUI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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