SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ceb8675e9a377546a6215825cbac72abd578e81f6fec78f720e46e93864efa0d' 
  AND token = '/1QEMnFFkbS/XTZ9lsznUISckUv5SLnY6p2RX8RwQak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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