SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27e89ede1cd54b9d693a3220b3bbbca27f8167076672610a3a56daf4b82736a9' 
  AND token = 'mn5sDpXNiOzInwsxJb/WwPcMCPn9rXu4h4NzdL2pKRw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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