SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a276ecdaf040d5c36f27ff69284ac1cc30a828e76ae796045d3dfa3e78d570f' 
  AND token = 'ElXJmfTOUX06swS68xnLkDF6IJKZ8ViMhG7OxGD3hw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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