SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1688901a163b498fa2670189fcd3881cc557d8f4e2f6fbd812be0e4942ae24d9' 
  AND token = 'Rkfo/RRGyIWDK7jGGLpkey+XiSNpWcC357EsqRiOHjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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