SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89325ee59eba883de94c75c065f94bbde2ee0c3734834f2354040af6d138d42d' 
  AND token = 'NKwz4AUooTKFMXXaq+PhULMvY51bSuIpBYcrFNM90Tw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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