SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eadc9a99ae1de3c364e14388384fd228c2ccfacd649bffa327ded45172f58947' 
  AND token = 'RXgiPlUiqAGaosWz5JOfHeZ+Gyi/RK4wuTUYhQQwaNU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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