SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38dbf78e91a959077bbe47cc91dc7d30f0874e00e74f1399e8e41da40344d278' 
  AND token = 'jgzbAK0pVhs5jqrUyL5JwJXfJNFPSu3K8esNYYKRGn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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