SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a1262ca7864de7026021becd0d977c0890a4a413f386f84a4bb8472755f99fb' 
  AND token = 'xAlcRJmj9uhPTvIxxgF8gqCN4BZ81iscBvU5JDAHr2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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