SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8eed3eaadba13e021e273ccaf9f1b40da9060db8870c147037c202bb8fd85aba' 
  AND token = '/yygxILSL74yUBle9sIlgw2di+cE6rlSkkhZ2BqNH4E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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