SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20a9117ae26fbc8eb501d270ff36c01dfbd078d093364efbc21cfe2ddf80c82a' 
  AND token = 'c3uR8XFhcwZFSGtZT8cge0hIPlTBjGE2NQfvLyaZTMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}