SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '429a3ae76729aa1dad2bfa5e7907cd541bc7c8a694ec7f7a916c0d9c85fe2f9e' 
  AND token = 'E1JCmEF7hJbJRqZ/BJtw5Yoy5l5CViFXpWOHrvSB+Po=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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