SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af5e15f2b837fb9b48cff2ddc7c552e8fae4f0c980cda1ea32b95a988c12d5bc' 
  AND token = 'uNLNQCUEj/PfOvsYLyXk/ZOpmAnpXRDRjeNRs+KyoUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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