SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34e39bead17342bf25bf3763951ed18fb701373e78662455b65ce8f404e28a95' 
  AND token = 'Zv4AcBd747sQYuVDPHgU1NJStzO/tK8hMJwxv0Gt090=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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