SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a6578a2ea2bd6176d4be14afd8d299a4ff747616a3098a0a1061f8495e6486e' 
  AND token = 'lwq3dznTx8lUyXkhmKUQGCxRnRP9NmgBtaYTMeW8HNQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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