SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5903aa9d5c675bd2db86b804e87a595113f4f1e18cc9fb8b663a4ac696a5a18b' 
  AND token = '3dYPmvuXfjzUZHUayK8Ae+uZvMQnDbtR7JI8RgzWLx0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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