SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c5e3b2cb547dd578693285b329c2faa64d5269191b69381e1523ca4fc2645bd' 
  AND token = 'R30UI1KaC0jyiZfi+IVc8qq1LjlVbQcPlP7zZiYR1BY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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