SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c681933633e88197c67223944886f4defa271540a3b815ddbad5bdb2e97d24c' 
  AND token = 'QRQwuesvAEol4sqb3Bxj159oLM21wSdb7kgDAjgV2LQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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