SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5713b432ef52ba12301a1574213378f09db18b09834148db7692824d6adddfda' 
  AND token = 'nsPbG+RtzLu6NvQEYrSE30g0ChWtcQxgHemSNmyKxiI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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