SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f42f5ab04e2a51979ea5f6b223732584d43fdfe11a48ad7f33de79c6d47c537f' 
  AND token = 'lDye+XE4bwNOntkdFBgXQHK8ih4uAFZjLTMqtskPhWI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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