SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec4d3b156f6eef3cf63165b0c4ad213d0381aca53dc08b9fa4e1109a9b6cbd70' 
  AND token = 'cJMnQYLsFv1tyfEVd1aC//OoOAiMAtNJw2qSwqMj4nI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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