SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac98b884e028762bdaef867a63c4f9c4a8aaed5703fb7d9a72535003ffe0d884' 
  AND token = 'o3y3cxnQdXb8fQCmrBabzFQfs0WevoXBCz8+4aUZRBo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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