SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83ebf92d5075f1e9ee4af3880bc7ce63d302bd9069f4a9f4c5edff9919ad631c' 
  AND token = 'tzrMbAwzUdj7XzJPtZRBMjj9v219CWRaGGmM4Uau4as=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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