SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8d910d9ea1e6b5f66b64f20bfa54d94a08b0a2953a33d4fa7eba1105772e34f' 
  AND token = 'nFeGTiTn+aBrtKxPnmfjJxhoogwLOWU2psZBaqHoEG0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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