SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '241aaf0f9e6185459027ac795f804e8e7465ebc8845c995e854f314f293e56bb' 
  AND token = 'PO5Z4dlVoO+kyK008zLCSzoOgsJqmlSseRh7aOUSx28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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