SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9f17edd34f4a0b675bfcc1fb46dd52e0391357313b36724ee2e95629a257d28' 
  AND token = 'Dl5pY45LvSXJu/qGVPBKV2fwGMgIkDwrROM6HsoRMrk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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