SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1256fffcf4b1b73f888693407a8bb514d4b79a339e479046d5c620f7e30c0a07' 
  AND token = 'wPSDeJWAR8zYh1gLeggq5lG69QZvUnBcy6cNBkXS0LI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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