SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52b8853a91b2733c70de738cf1a8e70f18337a5d2053de43162ef6aa007217f6' 
  AND token = 'fM/2ys8L+746NzLrEqZBNd2WviW/hPbnK/e2aqLBCqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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