SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2ddc79a8eff5ddee54a7829125e414136520ae68a798cf9729bf46c9aa74afa' 
  AND token = '3KShN5lejdSufeeBnqZdcHQpo3fNKJXu0fSDhUFeTT0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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