SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c36a98b89871dcca69c901d179c8bf649e309491b140e93cb6b9acd57c7d0fc' 
  AND token = 'l7wtV/AR7RUYRhwzJMGfHXVaK7QdqPDsMJn52bWhBvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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