SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eae320b501d81762a92c7e394b119da931ea73f4decad7b4b16122af39f9a259' 
  AND token = 'qF/IoPH/GANOgzNFPhUBtz3sS1tEDF05n+PNlFZ8Mz0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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