SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e261f85192db5afd4c53f6d21af355c3df71995bc8c4da7b3e5943ce87559a5' 
  AND token = 'vJXd5oahUDqkXD7+WVuPcO0wEpzyUH/LYsjBtr2qJ64=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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