SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c54480d83e8785e6bab79d282ad440daaaccb70ad426364f391e67332f8f3fea' 
  AND token = '+exU/U/hPxIpSwwRw4DVYqSUIxCsi27anzAzZAXZG24=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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