SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '974883fcd28560829288f0d89a8a544c85259934e19daf084f7c1991c53e00fa' 
  AND token = 'sds1DXbnkIYMF6zKX2/Nqy/ahRSp/N8gwv9qrDv77v0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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