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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9cafe0a298a6108043f528886dbc483c52849ae1fdec85c2d54e1d85ed6fe457' 
  AND token = 'VVAKbZCbQfM8iIYAuOcM5eJ9cpDuLxGkfDnmhC/JGU4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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