SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dca261677b5785fdb39a1350f451b26fcff2de79b498bb6d3f7de3963e1c5337' 
  AND token = 'l7YwpzO9vVlUZLSgYAI6ADqZ524MdGRGWHX5EmUSP9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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