SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '306f10489b6e6a873754c4463d129c56d772e59a76a21b077623b0a3a3cd14bc' 
  AND token = 'K0YuNkOykJ3ne8WZGFcHGhvMi5L/zl7a1tjyH6l9f5Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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