SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92083dc3f106ed5e99cdc7de383fa1a51d21dbd713394d5a1425faaaa33954d4' 
  AND token = 'u4dyMyUNqqHCFAaRWMsKXkPVrwOtkLPx8DRVDHfl/38=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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