SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4dc253cf5687477adeb8bddd86d6a6d13daa6ef3bddaca30575e2766ccd4cc3f' 
  AND token = '/QTG/jbMs6wv4AYMnjIsLGCvCUmmEwxNEaCRbrRXfk8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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