SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5f39868a4f37bd5657f6d2295cbd5002d601a8609a439fca6c63f2f9f17cd70' 
  AND token = 'OFMh8QnVq402JEMF1CivWqjSDgp+qdPAQwkyMzosdrI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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