SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'def7109638a822803bc0816c2c7c77622cbb412d5488edb3133e17d6707f1daa' 
  AND token = 'kj6GcHgsXIaAAHoq6pZe+LvaSNrwLtlkZWnljeoxVpw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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