SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b9c726da3dac4b57a06e0c8e3642298e7f78416a5e60003a96114620509e884' 
  AND token = 'ynyduKn/q4BOJmdlzWwcuyCr70ipIriSuyDy988MiZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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