SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cb0c725ddafec85d5d32b9abe3e6cf5ee7adf060bd77fada87509dbfcf7faa7f' 
  AND token = '/7AKvDGLiymnsi8ede5xgD1Lq4jGZtsgqMIaVJNEoeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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