SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4ba2006fcdf7f292e5be8126b7d3ff9fb3443b0b97aa7a2ad1555abde77d6bb' 
  AND token = '4u9PzpUGb4aRDcsJVehNjhwmRsw32UrKoFCBYlDJVv0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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