SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c4cefdc6a4b3796b6dc55eb50823add476234c4970db0e4713c7509ad38a738' 
  AND token = 'CC/Xs0/MCQelLfucrJsdyfm1fxquv8z2zwwUePJjgxY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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