SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de55b22d139829477bcbe15e658f1a4ec6e38c995bb05dd2878485d7d8f160c9' 
  AND token = 'WSZ9DKoKDjDgRitspRJ5Z8chTCKTtWChRejpGOkpthc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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