SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cc83829bdba12db9a7d940c388b8f7fe7e9417b967eee663a5d856a7457c5079' 
  AND token = 'cbTqVUz+M2jyTQXmmxVSQfpXHkPOBiDnHJlZlCokyGY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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