SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afa826c6913e49f13b7fbfd3cb33369da83e9297e42f56c713f4b3afc11ba4f6' 
  AND token = 'BrwYsJlq1d9gczQE+MPYJKtVIGl4fYJh5aSX2KmijHA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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