SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77dcb131a182d2241906701e510084c9c27c07f81f6a72c66b753455e9712225' 
  AND token = 'wl7lymDXFyE4pBLqCKdXjAXDfjq4ON+RKXrwjM9MKbU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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