SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9cd3641061ffd81ed971c82374010da26cb73aef2959bbfd75f29942a2c11799' 
  AND token = '48U16fPvZMnflUQg09I+NAUW/kTMbD8AqzRstnUyZns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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