SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6b8779ad015abd64691b114876d5becd1246d8dd65b31b06bf389f856fee533' 
  AND token = '+4uLK4Kksq/wPWli9E7OpjCWJlsCajdQo7b/oGT+vXY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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