SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96dfa2b5e307582884da44a217452025a93e796b257defea933828e4fbc329f2' 
  AND token = '4DpRo5W7JDJ2Kbb8XAFcackQhIovPebjcUW3cjjGP0Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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