SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ecb9046fb36374692550043d44f03260c84b47183f31a5403fc9c22cc65eafb7' 
  AND token = 'zl2FQN+WLJTM5dhTQKqXTyPMOb9qjDQbKtM0aJ/5DI8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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