SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5b7e2e548ed31444099068922ba0f185b473a2aa05658dac103c7fdeeaf44fb' 
  AND token = '1KUqn78fKGczuxSZ6o3/ElocCWzvtI8rifmgTKGL/LY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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