SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a067c2840cfaf5f05621b0dffba50649289a70a8d0fa1ba1422ab8927249b9de' 
  AND token = '3wgmnzLGnryIUaeMtHqaFOxo+Qu9vNaTTUr5xLWZ1BM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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