SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a6dd9f7b269a040bb0d81f4f208e335d6334d25492a3b79f08971473bc4f899' 
  AND token = 'lZK/8jKvEC3rFVIx+4IfY7vh49u8olziXqtKuhfxEPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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