SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4048233b4751001f2d3cda7f7a5b02ee23a95f8c211650c3ff3ba7d4c294f4f1' 
  AND token = 'OP/v+zA6hi2m/GKjBIUV3oHsvsMwvB+GkdAxpRjFvzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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